Publications

An up-to-date list is available on Google Scholar , also on Web of Science.

Publication Summary

Full List

2024

1. Small Polaron Dynamics in a Two-dimensional Magnetic Material
   Yao, Li^#; Wang, Aolei; Zheng, Qijing*; Zhao, Jin*
   Physical Review B, 110, 054305 (2024)
   Published: Aug, 2024
   Link bibtex abstract

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   The polaron in magnetic materials can carry not only charge, but also spin information. Therefore, the polaron dynamics in magnetic material is directly correlated with the spin dynamics. In this work, taking two-dimensional (2D) CoCl2 as a prototypical system, it is found that the 2D transition metal dihalide is an ideal platform for small polaron formation. At zero temperature, three distinct structures of small polarons, with their charges mainly localized on one, two, and three Co atoms, have been identified and designated as polarons I, II, and III, respectively. Polarons II and III are stable at 300 K, and their site-to-site hopping involves the transition to each other. Notable in-plane spin canting is observed when polaron II is formed. Moreover, the photoexcited charge carrier lifetime for the spin-minority channel is distinctly reduced by the spin-polarized polaron state in the band gap, making it four orders of magnitude shorter than the spin-majority channel. The existence of a small polaron in 2D magnetic materials provides a different stratagem to design 2D spintronic and polaronic devices.

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   @article{Yao2024,
     author = {Yao, Li and Wang, Aolei and Zheng, Qijing and Zhao, Jin},
     first_authors = {Yao Li},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     author+an = {1=first; 3=highlight,corresponding; 4=corresponding},
     doi = {10.1103/PhysRevB.110.054305},
     issn = {2469-9950},
     journal = {Physical Review B},
     month = aug,
     number = {5},
     pages = {054305},
     title = {{Small Polaron Dynamics in a Two-dimensional Magnetic Material}},
     volume = {110},
     year = {2024}
   }
    

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2. Vertical Dipole Dominates Charge Carrier Lifetime in Monolayer Janus MoSSe
   Fu, Cen-Feng^#; Zheng, Qijing; Li, Xingxing*; Yang, Jinlong*
   Nano Letters, 24, 6425–6432 (2024)
   Published: May, 2024
   Link bibtex abstract

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   Two-dimensional semiconductor materials with vertical dipoles are promising photocatalysts as vertical dipoles not only promote the electron–hole separation but also enhance the carrier redox ability. However, the influence of vertical dipoles on carrier recombination in such materials, especially the competing relationship between vertical dipoles and band gaps, is not yet clear. Herein, first-principles calculations and nonadiabatic molecular dynamics simulations were combined to clarify the influence of band gap and vertical dipole on the carrier lifetime in Janus MoSSe monolayer. By comparing with the results of MoS2 and MoSe2 as well as exploring the carrier lifetime of MoSSe under strain regulation, it has been demonstrated that the vertical dipole, rather than the band gap, is the dominant factor affecting the carrier lifetime. Strikingly, a linear relationship between the carrier lifetime and vertical dipole is revealed. These findings have important implications for the design of high-performance photocatalysts and optoelectronic devices.

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   @article{Fu2024,
     author = {Fu, Cen-Feng and Zheng, Qijing and Li, Xingxing and Yang, Jinlong},
     first_authors = {Fu Cen-Feng},
     corresponding_authors = {Li Xingxing, Yang Jinlong},
     author+an = {1=first; 2=highlight; 3=corresponding; 4=corresponding},
     doi = {10.1021/acs.nanolett.4c01577},
     issn = {1530-6984},
     journal = {Nano Letters},
     month = may,
     number = {21},
     pages = {6425--6432},
     title = {{Vertical Dipole Dominates Charge Carrier Lifetime in Monolayer Janus MoSSe}},
     volume = {24},
     year = {2024}
   }
    

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3. Spontaneous Polarization Dynamics in V-doped Monolayer MoS₂
   Xu, Jinhong^#; Zheng, Qijing*; Zhao, Jin*
   Computational Materials Today, 1, 100004 (2024)
   Published: May, 2024
   Link bibtex abstract

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   Valleytronics has drawn attention both for its fundamental aspects and potential applications in device technology. Lifting the valley degeneracy is an attractive route to achieve stable valley polarization and spontaneous valley polarization. Our first-principles calculations on V-doped monolayer MoS2 reveal a substantial permanent valley splitting of 174 meV, driven by the combined effects of spin-orbit coupling (SOC) and magnetic coupling with the doped atom. Non-adiabatic molecular dynamics simulations show that the spontaneous valley polarization dynamics depends on the SOC, electron-phonon (e-ph) coupling and the scattering with the impurity, and it varies notably with different initial spin orientations of excited holes. For spin-up holes, the process involves e-ph scattering and spin-flip induced by spinor-phonon scattering over several picoseconds. On the other hand, spin-down hole excitation leads to spontaneous polarization through e-ph and impurity scattering on a timescale shorter by an order of magnitude. This study provides insights into the distinct valley polarization dynamics of carriers with different spins, contributing to the design of ultrafast valleytronic and spintronic devices.

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   @article{Xu2024,
     author = {Xu, Jinhong and Zheng, Qijing and Zhao, Jin},
     first_authors = {Xu Jinhong},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     author+an = {1=first; 2=highlight,corresponding; 3=corresponding},
     doi = {10.1016/j.commt.2024.100004},
     issn = {29504635},
     journal = {Comput. Mater. Today},
     month = may,
     pages = {100004},
     title = {{Spontaneous Polarization Dynamics in V-doped Monolayer MoS2}},
     volume = {1},
     year = {2024}
   }
    

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4. Real-Time Ab Initio Investigation on Hot Electron Relaxation Dynamics in Silicon
   Wang, Zhenyu^#; Zheng, Zhenfa*; Zheng, Qijing*; Zhao, Jin*
   Journal of Physical Chemistry Letters, 15, 3907–3913 (2024)
   Published: Apr, 2024
   Link bibtex abstract

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   The relaxation of hot electrons in semiconductors is pivotal for both energy harvesting processes and optoelectronics. Utilizing a self-developed non-adiabatic molecular dynamics simulation approach in the momentum space (NAMD_k), we have examined the dynamics of hot electrons in silicon. Whether excited from the Γ or L point, the relaxation dynamics exhibit two distinct stages. Initially, within 100 fs, electrons scatter with phonons throughout the Brillouin zone. Subsequently, over a few picoseconds, they further relax toward the conduction band minimum as a whole. This picture of hot electron relaxation is highly consistent with the quasi-equilibrium hot electron ensemble (HEE) concept. Throughout the hot electron relaxation process, energy transfer to phonons is efficient, leading to time-dependent phonon excitation, which is thoroughly analyzed. This investigation provides a novel perspective on hot electron relaxation in silicon, which holds substantive implications for the realm of photovoltaic and optoelectronic device applications.

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   @article{Wang2024,
     author = {Wang, Zhenyu and Zheng, Zhenfa and Zheng, Qijing and Zhao, Jin},
     doi = {10.1021/acs.jpclett.4c00591},
     issn = {1948-7185},
     journal = {Journal of Physical Chemistry Letters},
     author+an = {1=first; 2=corresponding; 3=highlight,corresponding; 4=corresponding},
     first_authors = {Wang Zhenyu},
     corresponding_authors = {Zhao Jin, Zheng Qijing, Zheng Zhenfa},
     month = apr,
     number = {14},
     pages = {3907--3913},
     title = {{Real-Time Ab Initio Investigation on Hot Electron Relaxation Dynamics in Silicon}},
     volume = {15},
     year = {2024}
   }
    

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5. Photoexcitation-induced Spin Dynamics in 1T-VSe₂ Investigated by Ab Initio Nonadiabatic Molecular Dynamics
   Chen, Linjie^#; Zheng, Zhenfa; Zheng, Qijing*; Li, Qunxiang*; Zhao, Jin*
   Science China Materials, 67, 1253–1259 (2024)
   Published: Apr, 2024
   Link bibtex abstract

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   Using photoexcitation to manipulate the magnetic moment in two-dimensional (2D) materials paves the way for the design of opto-spintronic devices. In this work, using ab initio nonadiabatic molecular dynamics simulation, we studied how photoexcitation changed the magnetic moment in the 2D ferromagnetic metal VSe2. The spin-orbit coupling and phonon excitation lead to the loss of the original spin orientation in both the spin-up and spin-down orbitals, forming a spin-mixing region approximately 1.0 eV above the Fermi level. When spin-up or spin-down electrons pass through this region during relaxation, they lose their original spin orientation. However, spin-down electrons relax approximately an order of magnitude faster than spin-up electrons, as the relaxation for spin-down is primarily intraband, while spin-up electrons undergo interband relaxation. Such different dynamical behaviors for spin-up and spin-down electrons result in the magnetic moment of VSe2 initially rising within approximately 10 fs after optical excitation, corresponding to the loss of the original spin orientation for spin-down electrons. Subsequently, it decreases by approximately 100 fs, corresponding to the loss of spin orientation for spin-up electrons. Finally, the total magnetic moment of the system gradually recovers to the preexcitation level on the order of picoseconds. This work provides new insight into how photoexcitation controls the magnetic properties of 2D materials.

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   @article{Chen2024,
     author = {Chen, Linjie and Zheng, Zhenfa and Zheng, Qijing and Li, Qunxiang and Zhao, Jin},
     doi = {10.1007/s40843-023-2838-5},
     issn = {2095-8226},
     journal = {Science China Materials},
     author+an = {1=first; 3=highlight,corresponding; 4=corresponding; 5=corresponding},
     first_authors = {Chen Linjie},
     corresponding_authors = {Zhao Jin, Zheng Qijing, Li Qunxiang},
     month = apr,
     number = {4},
     pages = {1253--1259},
     title = {{Photoexcitation-induced Spin Dynamics in 1T-VSe2 Investigated by Ab Initio Nonadiabatic Molecular Dynamics}},
     volume = {67},
     year = {2024}
   }
    

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2023

1. Ab Initio Investigation on Exciton-phonon Interaction and Exciton Mobility in Black Phosphorene
   Tian, Xirui^#; Zheng, Qijing; Jiang, Xiang*; Zhao, Jin*
   Physical Review B, 108, 245118 (2023)
   Published: Dec, 2023
   Link bibtex abstract

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   Black phosphorene (BP) is an emerging two-dimensional material that has potentially wide applications in nano- and optoelectronics. Despite the strong excitonic effects observed in few-layer BP, there is still a lack of understanding regarding exciton-phonon (ex-ph) interaction and exciton mobility. In this work, using GW plus real-time Bethe-Salpeter equation approach, it is revealed that the out-of-plane acoustic phonon mode ZA , and the optical phonon modes A1g and A2g couple strongly with the exciton. Among them, the A2g mode has a uniquely significant influence on the oscillator strength. Driven by these ex-ph interactions, the exciton becomes more localized accompanied with strengthened binding and the absorption spectrum undergoes a notable renormalization at 300 K. In the framework of deformation potential theory, the exciton mobility of monolayer BP (MLBP) is found to be largely suppressed compared to the free-charge carriers, showing quasi-one-dimensional character. This work provides rich knowledge of ex-ph interaction and exciton mobility in MLBP at the ab initio level, offering insights for the understanding and controlling the exciton behavior in BP-based devices.

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   @article{Tian2023,
     author = {Tian, Xirui and Zheng, Qijing and Jiang, Xiang and Zhao, Jin},
     author+an = {1=first; 2=highlight; 3=corresponding; 4=corresponding},
     first_authors = {Tian Xirui},
     corresponding_authors = {Zhao Jin, Jiang Xiang},
     doi = {10.1103/PhysRevB.108.245118},
     issn = {2469-9950},
     journal = {Physical Review B},
     month = dec,
     number = {24},
     pages = {245118},
     title = {\textit{Ab Initio} {Investigation on Exciton-phonon Interaction and Exciton Mobility in Black Phosphorene}},
     volume = {108},
     year = {2023}
   }
    

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2. Ultrafast Many-body Bright–dark Exciton Transition in Anatase TiO₂
   Wang, Aolei^#; Jiang, Xiang*; Zheng, Qijing; Petek, Hrvoje; Zhao, Jin*
   Proc. Natl. Acad. Sci., 120, e2307671120 (2023)
   Published: Nov, 2023
   Link bibtex abstract

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   The momentum-forbidden dark excitons can have a pivotal role in quantum information processing, Bose–Einstein condensation, and light-energy harvesting. Anatase TiO 2 with an indirect band gap is a prototypical platform to study bright to momentum-forbidden dark exciton transition. Here, we examine, by GW plus the real-time Bethe–Salpeter equation combined with the nonadiabatic molecular dynamics (GW + rtBSE-NAMD), the many-body transition that occurs within 100 fs from the optically excited bright to the strongly bound momentum-forbidden dark excitons in anatase TiO 2 . Comparing with the single-particle picture in which the exciton transition is considered to occur through electron–phonon scattering, within the GW + rtBSE-NAMD framework, the many-body electron–hole Coulomb interaction activates additional exciton relaxation channels to notably accelerate the exciton transition in competition with other radiative and nonradiative processes. The existence of dark excitons and ultrafast bright–dark exciton transitions sheds insights into applications of anatase TiO 2 in optoelectronic devices and light-energy harvesting as well as the formation process of dark excitons in semiconductors.

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   @article{Wang2023,
     author = {Wang, Aolei and Jiang, Xiang and Zheng, Qijing and Petek, Hrvoje and Zhao, Jin},
     author+an = {1=first; 2=corresponding; 3=highlight; 5=corresponding},
     first_authors = {Wang Aolei},
     corresponding_authors = {Zhao Jin, Jiang Xiang},
     doi = {10.1073/pnas.2307671120},
     issn = {0027-8424},
     journal = {Proc. Natl. Acad. Sci.},
     month = nov,
     number = {47},
     pages = {e2307671120},
     title = {Ultrafast Many-body Bright–dark Exciton Transition in Anatase TiO2},
     volume = {120},
     year = {2023}
   }
    

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3. Resonant Charge Transport Assisted by the Molecular Vibration in Single-Molecule Junction from Time-Domain Ab Initio Nonadiabatic Molecular Dynamics Simulations
   Tian, Yunzhe^#; Zheng, Qijing*; Zhao, Jin*
   Chinese Physics Letters, 40, 126301 (2023)
   Published: Nov, 2023
   Link bibtex abstract

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   Using ab initio nonadiabatic molecular dynamics simulation, we study the time-dependent charge transport dynamics in a single-molecule junction formed by gold (Au) electrodes and a single benzene-1,4-dithiol (BDT) molecule. Two different types of charge transport channels are found in the simulation. One is the routine non-resonant charge transfer path, which occurs in several picoseconds. The other is activated when the electronic state of the electrodes and that of the molecule get close in energy, which is referred to as the resonant charge transport. More strikingly, the resonant charge transfer occurs in an ultrafast manner within 100 fs, which notably increases the conductance of the device. Further analysis shows that the resonant charge transport is directly assisted by the B 2 and A 1 molecular vibration modes. Our study provides atomic insights into the time-dependent charge transport dynamics in single-molecule junctions, which is important for designing highly efficient single-molecule devices.

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   @article{TianYZ2023,
     author = {Tian, Yunzhe and Zheng, Qijing and Zhao, Jin},
     author+an = {1=first; 2=highlight,corresponding; 3=corresponding},
     first_authors = {Tian Yunzhe},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     doi = {10.1088/0256-307X/40/12/126301},
     issn = {0256-307X},
     journal = {Chinese Physics Letters},
     month = nov,
     number = {12},
     pages = {126301},
     title = {{Resonant Charge Transport Assisted by the Molecular Vibration in Single-Molecule Junction from Time-Domain \textit{Ab Initio} Nonadiabatic Molecular Dynamics Simulations}},
     volume = {40},
     year = {2023}
   }
    

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4. Ab Initio Nonadiabatic Molecular Dynamics Study on Spin-Orbit Coupling Induced Spin Dynamics in Ferromagnetic Metals
   Zhu, Wansong^#; Zheng, Zhenfa; Zheng, Qijing*; Zhao, Jin*
   Chinese Physics B, 33, 016301 (2023)
   Published: Sep, 2023
   Link bibtex abstract

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   Understanding the photoexcitation induced spin dynamics in ferromagnetic metals are important for the design of photocontrolled ultrafast spintronic device. In this work, by the ab initio nonadiabatic molecular dynamics simulation, we have studied the spin dynamics induced by spin-orbit coupling (SOC) in Co and Fe using both spin-diabatic and spin-adiabatic representations. In Co system, it is found the Fermi surface (E F ) is predominantly contributed by the spin-minority states. The SOC induced spin flip will occur for the photoexcited spin-majority electrons as they relax to the E F , and the spin-minority electrons tend to relax to the E F with the same spin through the electron-phonon coupling (EPC). The reduction of spin-majority electrons and the increase of spin-minority electrons lead to demagnetization of Co within 100 fs. By contrast, in Fe system, the E F is dominated by the spin-majority states. In this case, the SOC induced spin flip occurs for the photo-excited spin-minority electrons, which leads to a magnetization enhancement. If we move the E F of Fe to higher energy by 0.6 eV, the E F will be contributed by the spin-minority states and the demagnetization will be observed again. This work provides a new perspective for understanding the SOC induced spin dynamics mechanism in magnetic metal systems.

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   @article{Zhu2023,
     author = {Zhu, Wansong and Zheng, Zhenfa and Zheng, Qijing and Zhao, Jin},
     author+an = {1=first; 3=highlight,corresponding; 4=corresponding},
     first_authors = {Zhu Wansong},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     doi = {10.1088/1674-1056/acf91d},
     issn = {1674-1056},
     journal = {Chinese Physics B},
     month = sep,
     pages = {016301},
     title = {\textit{Ab Initio} {Nonadiabatic Molecular Dynamics Study on Spin-Orbit Coupling Induced Spin Dynamics in Ferromagnetic Metals}},
     volume = {33},
     year = {2023}
   }
    

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5. Ab Initio Real-time Quantum Dynamics of Charge Carriers in Momentum Space
   Zheng, Zhenfa^#; Shi, Yongliang*; Zhou, Jin-Jian; Prezhdo, Oleg V.; Zheng, Qijing*; Zhao, Jin*
   Nature Computational Science, 3, 532–541 (2023)
   Published: Jun, 2023
   Link bibtex abstract PDF

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   Application of the non-adiabatic molecular dynamics (NAMD) approach is limited to studying carrier dynamics in the momentum space, as a supercell is required to sample the phonon excitation and electron–phonon (e–ph) interaction at different momenta in a molecular dynamics simulation. Here we develop an ab initio approach for the real-time charge carrier quantum dynamics in the momentum space (NAMD_k) by directly introducing e–ph coupling into the Hamiltonian based on the harmonic approximation. The NAMD_k approach maintains the zero-point energy and includes memory effects of carrier dynamics. The application of NAMD_k to the hot carrier dynamics in graphene reveals the phonon-specific relaxation mechanism. An energy threshold of 0.2 eV—defined by two optical phonon modes—separates the hot electron relaxation into fast and slow regions with lifetimes of pico- and nanoseconds, respectively. The NAMD_k approach provides an effective tool to understand real-time carrier dynamics in the momentum space for different materials.

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   @article{ZhengZ_2023_NatCompSci,
     title = {\textit{Ab Initio} {Real-time Quantum Dynamics of Charge Carriers in Momentum Space}},
     author+an = {1=first; 2=corresponding; 5=corresponding,highlight; 6=corresponding},
     author = {Zheng, Zhenfa and Shi, Yongliang and Zhou, Jin-Jian and Prezhdo, Oleg V. and Zheng, Qijing and Zhao, Jin},
     pdf = {/assets/pdf/pubs/Zhengzhenfa_NatCompSci_2023.pdf},
     first_authors = {Zheng Zhenfa},
     corresponding_authors = {Zhao Jin, Zheng Qijing, Shi Yongliang},
     doi = {10.1038/s43588-023-00456-9},
     journal = {Nature Computational Science},
     publisher = {Springer Nature},
     month = jun,
     volume = {3},
     pages = {532--541},
     year = {2023}
   }
    

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6. Research on Quantum Proton Coupled Charge Transfer Process Based on Deep Neural Network
   Tu, Youyou^#; Zheng, Qijing*; Zhao, Jin*
   Frontiers of Data and Computing, 5, 37–49 (2023)
   Published: Apr, 2023
   Link bibtex abstract

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   [Objective] Understanding the physical mechanism of ultrafast charge transfer at the molecule/solid interfaces plays a crucial role in improving the energy conversion efficiency of solar cells and photocatalytic reactions. [Scope of the literature] At many molecules/solid interfaces containing hydrogen, molecules adsorption forms a certain structure, then molecular hydrogen ions can form the hydrogen bond (H-bond) network on the surface. Because of the very light mass of hydrogen, and its frequent existence in the form of proton in molecules, one can often observe the charge transfer process in which protons couple with electrons at the molecule/solid interface, and the nuclear quantum effects (NQEs) of proton cannot be ignored in these processes. Recently, we developed a computational method RP-NAMD combining path-integral molecular dynamics (PIMD) and nonadiabatic molecular dynamics (NAMD), which can effectively study the proton-charge coupled charge transfer process. However, the huge amount of computation required by PIMD/RPMD limits the application of these methods in real systems. [Methods] In this paper, we use the deep learning method to greatly reduce the computational cost of PIMD/RPMD, so that RP-NAMD can be applied to larger systems and can be used to study dynamical processes at a longer time scale. To validate this new method, we chose the CH3OH/anatase TiO2 interface as a practical system and investigated the important role of nuclear quantum effects in the interfacial proton-coupled charge transfer process. [Conclusions] In short, based on deep learning, this paper provides a practical calculation method that can be used to study the coupling between nuclear quantum effects and carrier dynamics.

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   @article{Tuyy2023_FDD,
     title = {{Research on Quantum Proton Coupled Charge Transfer Process Based on Deep Neural Network}},
     author = {Tu, Youyou and Zheng, Qijing and Zhao, Jin},
     first_authors = {Tu Youyou},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     author+an = {1=first; 2=highlight,corresponding; 3=corresponding;},
     journal = {Frontiers of Data and Computing},
     doi = {10.11871/jfdc.issn.2096-742X.2023.02.003},
     month = apr,
     number = {2},
     pages = {37--49},
     volume = {5},
     year = {2023}
   }
    

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2022

1. Excited Electron and Spin Dynamics in Topological Insulator: A Perspective from Ab Initio Non-adiabatic Molecular Dynamics
   Zhao, Chuanyu^#; Zheng, Qijing; Zhao, Jin*
   Fundamental Research, 2, 506–510 (2022)
   Published: Jul, 2022
   Link bibtex abstract

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   We perform an ab initio non-adiabatic molecular dynamics simulation to investigate the non-equilibrium spin and electron dynamics in a prototypical topological insulator (TI) Bi2Se3. Different from the ground state, we reveal that backscattering can happen in an oscillating manner between time-reversal pair topological surface states (TSSs) in the non-equilibrium dynamics. Analysis shows the phonon excitation induces orbital composition change by electron-phonon interaction, which further stimulates spin canting through spin-orbit coupling. The spin canting of time-reversal pair TSSs leads to the non-zero non-adiabatic coupling between them and then issues in backscattering. Both the spin canting and backscattering result in ultrafast spin relaxation with a timescale around 100 fs. This study provides critical insights into the non-equilibrium electron and spin dynamics in TI at the ab initio level and paves a way for the design of ultrafast spintronic materials.

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   @article{ZHAO2022,
     author = {Zhao, Chuanyu and Zheng, Qijing and Zhao, Jin},
     doi = {10.1016/j.fmre.2022.03.006},
     issn = {26673258},
     journal = {Fundamental Research},
     first_authors = {Zhao Chuanyu},
     corresponding_authors = {Zhao Jin},
     author+an = {1=first; 2=highlight; 3=corresponding;},
     month = jul,
     number = {4},
     pages = {506--510},
     title = {{Excited Electron and Spin Dynamics in Topological Insulator: A Perspective from \textit{Ab Initio} Non-adiabatic Molecular Dynamics}},
     volume = {2},
     year = {2022}
   }
    

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2. Ultrafast Charge Transfer Coupled to Quantum Proton Motion at Molecule/Metal Oxide Interface
   Chu, Weibin^#; Tan, Shijing; Zheng, Qijing; Fang, Wei; Feng, Yexin; Prezhdo, Oleg V.; Wang, Bing; Li, Xinzheng*; Zhao, Jin*
   Science Advances, 8, eabo2675 (2022)
   Published: Jun, 2022
   Link bibtex abstract

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   Understanding how the nuclear quantum effects (NQEs) in the hydrogen bond (H-bond) network influence the photoexcited charge transfer at semiconductor/molecule interface is a challenging problem. By combining two kinds of emerging molecular dynamics methods at the ab initio level, the path integral–based molecular dynamics and time-dependent nonadiabatic molecular dynamics, and choosing CH 3 OH/TiO 2 as a prototypical system to study, we find that the quantum proton motion in the H-bond network is strongly coupled with the ultrafast photoexcited charge dynamics at the interface. The hole trapping ability of the adsorbed methanol molecule is notably enhanced by the NQEs, and thus, it behaves as a hole scavenger on titanium dioxide. The critical role of the H-bond network is confirmed by in situ scanning tunneling microscope measurements with ultraviolet light illumination. It is concluded the quantum proton motion in the H-bond network plays a critical role in influencing the energy conversion efficiency based on photoexcitation.

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   ×

   @article{Chu_SciAdv_2022,
     title = {{Ultrafast Charge Transfer Coupled to Quantum Proton Motion at Molecule/Metal Oxide Interface}},
     author = {Chu, Weibin and Tan, Shijing and Zheng, Qijing and Fang, Wei and Feng, Yexin and Prezhdo, Oleg V. and Wang, Bing and Li, Xinzheng and Zhao, Jin},
     first_authors = {Chu Weibin},
     corresponding_authors = {Li Xinzheng, Zhao Jin},
     author+an = {1=first; 3=highlight; 8=corresponding; 9=corresponding},
     doi = {10.1126/sciadv.abo2675},
     issn = {2375-2548},
     journal = {Science Advances},
     month = jun,
     number = {24},
     volume = {8},
     pages = {eabo2675},
     year = {2022}
   }
    

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3. High Photoreactivity on a Reconstructed Anatase TiO₂(001) Surface Predicted by Ab Initio Nonadiabatic Molecular Dynamics
   Tu, Youyou^#; Chu, Weibin; Shi, Yongliang; Zhu, Wenguang; Zheng, Qijing*; Zhao, Jin*
   Journal of Physical Chemistry Letters, 13, 5766–5775 (2022)
   Published: Jun, 2022
   Link bibtex abstract

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   Anatase TiO2(001) surface with (4 × 1) reconstruction is proposed to be a highly active catalytic surface. In this work, using time-domain ab initio nonadiabatic molecular dynamics, we reveal that the ridge structure formed by anatase(001) surface reconstruction is the photoreactive site for hole migration and trapping. Moreover, the ridge structure is destroyed by low-coverage CH3OH adsorption, leading to the suppression of its high photoreactivity. However, when the CH3OH coverage is increased and intermolecular hydrogen bonds (H-bonds) form, the ridge structure and its high photoreactivity are restored. Furthermore, the hole trapping dynamics is strongly coherent with intermolecular proton transfer in structures with intermolecular H-bonds. Our study proves that anatase TiO2(001)-(4 × 1) is a highly photoreactive surface where the ridge is the photoreactive site for hole trapping, which is coherent with the proton transfer process.

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   @article{Tu2022,
     author = {Tu, Youyou and Chu, Weibin and Shi, Yongliang and Zhu, Wenguang and Zheng, Qijing and Zhao, Jin},
     first_authors = {Tu Youyou},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     author+an = {1=first; 5=highlight,corresponding; 6=corresponding;},
     doi = {10.1021/acs.jpclett.2c01417},
     issn = {1948-7185},
     journal = {Journal of Physical Chemistry Letters},
     month = jun,
     pages = {5766--5775},
     title = {{High Photoreactivity on a Reconstructed Anatase TiO2(001) Surface Predicted by \textit{Ab Initio} Nonadiabatic Molecular Dynamics}},
     volume = {13},
     year = {2022}
   }
    

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4. Spin-orbit Coupling Induced Demagnetization in Ni: Ab Initio Nonadiabatic Molecular Dynamics Perspective
   Zheng, Zhenfa^#; Zheng, Qijing*; Zhao, Jin*
   Physical Review B, 105, 085142 (2022)
   Published: Feb, 2022
   Link bibtex abstract PDF

   ×

   Spin-orbit coupling (SOC), which can induce spin flip during the relaxation of photoexcited charge carrier, plays a crucial role in spin dynamics. In this work, we have used time-domain ab initio nonadiabatic molecular dynamics (NAMD) method to study the SOC induced ultrafast demagnetization in Ni at 300 K . The spin-diabatic representation using spin-polarized Kohn-Sham (KS) basis sets and spin-adiabatic representation using spinor basis sets have been applied, and both of them achieve demagnetization in Ni with a timescale around 100 fs . The spin-diabatic representation suggests a picture that the electron-phonon coupling (EPC) provides direct energy relaxation channel among the same-spin states, while the SOC can induce spin flip. After photoexcitation, it is found the spin-minority electrons relax to the same-spin states rather than the opposite-spin states, since EPC is larger than SOC by one order of magnitude. By contrast, for the spin-majority electrons, spin flip occurs since there are no empty same-spin states as electron acceptor above the Fermi level. The different relaxation pathways for spin-majority and spin-minority electrons induce the demagnetization. The spin-adiabatic representation provides an Elliott-Yafet spin-phonon scattering picture. The SOC induced reduction of magnetic moment in Ni may induce magnon to drive further demagnetization. The ab initio NAMD simulation provides a critical angle to understand how the SOC and EPC affect demagnetization process in Ni.

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   ×

   @article{ZZF_PRB_2022,
     title = {{Spin-orbit Coupling Induced Demagnetization in Ni: \textit{Ab Initio} Nonadiabatic Molecular Dynamics Perspective}},
     author = {Zheng, Zhenfa and Zheng, Qijing and Zhao, Jin},
     first_authors = {Zheng Zhenfa},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     author+an = {1=first; 2=highlight,corresponding; 3=corresponding},
     journal = {Physical Review B},
     volume = {105},
     issue = {8},
     pages = {085142},
     numpages = {7},
     year = {2022},
     month = feb,
     publisher = {American Physical Society},
     doi = {10.1103/PhysRevB.105.085142},
     pdf = {/assets/pdf/pubs/Zhengzhenfa_PRB_2022.pdf}
   }
    

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5. Effects of Oxygen Vacancies on the Photoexcited Carrier Lifetime in Rutile TiO₂
   Zhang, Lili^#; Chu, Weibin; Zheng, Qijing*; Zhao, Jin*
   Physical Chemistry Chemical Physics, 24, 4743–4750 (2022)
   Published: Jan, 2022
   Link bibtex abstract

   ×

   The photoexcited carrier lifetime in semiconductors plays a crucial role in solar energy conversion processes. The defects or impurities in semiconductors are usually proposed to introduce electron–hole (e–h) recombination centers and consequently reduce the photoexcited carrier lifetime. In this report, we investigate the effects of oxygen vacancies (OV) on the carrier lifetime in rutile TiO2, which has important applications in photocatalysis and photovoltaics. It is found that an OV introduces two excess electrons which form two defect states in the band gap. The lower state is localized on one Ti atom and behaves as a small polaron, and the higher one is a hybrid state contributed by three Ti atoms around the OV. Both the polaron and hybrid states exhibit strong electron–phonon (e–ph) coupling and their charge distributions become more and more delocalized when the temperature increases from 100 to 700 K. Such strong e–ph coupling and charge delocalization enhance the nonadibatic coupling between the electronic states along the hole relaxation path, where the defect states behave as intermediate states, leading to a distinct acceleration of e–h recombination. Our study provides valuable insights to understand the role of defects on photoexcited carrier lifetime in semiconductors.

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   ×

   @article{Zhang_PCCP_2022,
     title = {{Effects of Oxygen Vacancies on the Photoexcited Carrier Lifetime in Rutile TiO2}},
     author = {Zhang, Lili and Chu, Weibin and Zheng, Qijing and Zhao, Jin},
     author+an = {1=first; 3=corresponding,highlight; 4=corresponding},
     first_authors = {Zhang Lili},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     doi = {10.1039/D1CP04248C},
     issn = {1463-9076},
     journal = {Physical Chemistry Chemical Physics},
     volume = {24},
     pages = {4743--4750},
     month = jan,
     year = {2022}
   }
    

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2021

1. Tuning the Lifetime of Photoexcited Small Polarons on Rutile TiO₂ Surface via Molecular Adsorption
   Gao, Chang^#; Zhang, Lili; Zheng, Qijing*; Zhao, Jin*
   Journal of Physical Chemistry C, 125, 27275–27282 (2021)
   Published: Dec, 2021
   Link bibtex abstract

   ×

   TiO2 is a famous wide-bandgap semiconductor which has important applications in photocatalysis and photovoltaics. In the solar energy conversion process, photoexcited electrons can be trapped by the lattice distortion and can form a small polaron, which can quench through electron–hole recombination. On the TiO2 surface, the molecule adsorption is proposed to play an important role to influence the dynamics of a photoexcited polaron. In this study, by ab initio nonadiabatic molecular dynamics simulation, we study the dynamics of a photoexcited small polaron in the rutile TiO2(110) surface system and the effects of H2O adsorption. It is found that the photoexcited electron can be trapped by the lattice distortion in the subsurface layer within 25 fs. The H2O adsorption stabilizes the polaron by further stretching the Ti–O bonds around it. In a comparison with the photoexcited free electrons, the formation of the polaron shortens the carrier lifetime distinctly due to the reduction of the energy difference with the photoexcited hole at the valence band maximum, and reinforcement of electron–phonon (e–ph) coupling. Moreover, the H2O adsorption is found to further reduce the photoexcited polaron lifetime by enhancing the e–ph coupling with high-frequency phonons. This work suggests that molecule adsorption provides a new stratagem to tune the lifetime of a photoexcited small polaron.

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   ×

   @article{Gao_JPCC_2021,
     annote = {doi: 10.1021/acs.jpcc.1c07697},
     author = {Gao, Chang and Zhang, Lili and Zheng, Qijing and Zhao, Jin},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     doi = {10.1021/acs.jpcc.1c07697},
     issn = {1932-7447},
     journal = {Journal of Physical Chemistry C},
     month = dec,
     number = {49},
     pages = {27275--27282},
     publisher = {American Chemical Society},
     title = {{Tuning the Lifetime of Photoexcited Small Polarons on Rutile TiO2 Surface via Molecular Adsorption}},
     url = {https://doi.org/10.1021/acs.jpcc.1c07697},
     volume = {125},
     year = {2021}
   }
    

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2. Ultrafast Ferroelectric Ordering on the Surface of a Topological Semimetal MoTe₂
   Dai, Yanan^#; Zheng, Qijing^#; Ziffer, Mark E; Rhodes, Daniel; Hone, James; Zhao, Jin*; Zhu, Xiaoyang*
   Nano Letters, 21, 9903–9908 (2021)
   Published: Nov, 2021
   Link bibtex abstract PDF

   ×

   Transient tuning of material properties by light usually requires intense laser fields in the nonlinear excitation regime. Here, we report ultrafast ferroelectric ordering on the surface of a paraelectric topological semimetal 1T’-MoTe2 in the linear excitation regime, with the order parameter directly proportional to the excitation intensity. The ferroelectric ordering, driven by a transient electric field created by electrons trapped ångstroms away from the surface in the image potential state (IPS), is evidenced in two-photon photoemission spectroscopy showing the energy relaxation rate proportional to IPS electron density, but with negligible change in the free-electron-like parallel dispersion. First-principles calculations reveal an improper ferroelectric ordering associated with an anharmonic interlayer shearing mode. Our findings demonstrate an ultrafast charge-based pathway for creating transient polarization orders.

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   ×

   @article{Dai2021,
     annote = {doi: 10.1021/acs.nanolett.1c02965},
     author = {Dai, Yanan and Zheng, Qijing and Ziffer, Mark E and Rhodes, Daniel and Hone, James and Zhao, Jin and Zhu, Xiaoyang},
     corresponding_authors = {Zhao Jin, Zhu Xiaoyang},
     first_authors = {Dai Yanan, Zheng Qijing},
     doi = {10.1021/acs.nanolett.1c02965},
     issn = {1530-6984},
     journal = {Nano Letters},
     month = nov,
     number = {23},
     pages = {9903--9908},
     volume = {21},
     publisher = {American Chemical Society},
     pdf = {/assets/pdf/pubs/DynZqj_NanoLett_2021.pdf},
     title = {{Ultrafast Ferroelectric Ordering on the Surface of a Topological Semimetal MoTe2}},
     url = {https://doi.org/10.1021/acs.nanolett.1c02965 https://pubs.acs.org/doi/10.1021/acs.nanolett.1c02965},
     year = {2021}
   }
    

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3. Phonon–phonon Interaction Assisted Electron–hole Recombination in WSe₂/hBN van der Waals Heterostructure
   Feng, Nan^#; Tian, Yunzhe; Han, Jian; Zheng, Zhenfa; Wang, Aolei; Zheng, Qijing; Zhao, Jin; Bi, Ke*; Xu, Ben*
   Journal of Applied Physics, 130, 205708 (2021)
   Published: Nov, 2021
   Link bibtex abstract

   ×

   Photogenerated charge carrier dynamics at the WSe2/hBN van der Waals interface play an important role in optical device applications. The carrier behavior has been argued to be related to the interlayer phonon–phonon interaction in the heterostructure. However, the effect of the interlayer coupling on the electron–hole recombination dynamics is still unclear. Using the ab initio nonadiabatic molecular dynamics approach, we investigate the photoexcited electron dynamics at the interface, which has a type I energy alignment. The out-of-plane phonon of hBN is found to strongly couple with the WSe2 out-of-plane A′1 phonon, enhancing the electron–phonon interaction and accelerating the electron–hole recombination compared to pristine WSe2. Our work provides valuable guidance on the design of novel two-dimensional optoelectronic and opto-phononic devices.

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   ×

   @article{FengNan_JAP2021,
     title = {Phonon–phonon Interaction Assisted Electron–hole Recombination in WSe2/hBN van der Waals Heterostructure},
     author = {Feng, Nan and Tian, Yunzhe and Han, Jian and Zheng, Zhenfa and Wang, Aolei and Zheng, Qijing and Zhao, Jin and Bi, Ke and Xu, Ben},
     first_authors = {Feng Nan},
     corresponding_authors = {Xu Ben, Bi Ke},
     journal = {Journal of Applied Physics},
     volume = {130},
     number = {20},
     pages = {205708},
     year = {2021},
     month = nov,
     doi = {10.1063/5.0070269}
   }
    

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4. Time- and Momentum-resolved Image-potential States of 2H-MoS₂ Surface
   Liu, Jianyi^#; Jiang, Xiang; Li, Xintong; Ma, Xiaochuan; Sun, Xia; Zheng, Qijing; Cui, Xuefeng*; Tan, Shijing; Zhao, Jin*; Wang, Bing*
   Physical Chemistry Chemical Physics, 23, 26336–26342 (2021)
   Published: Nov, 2021
   Link bibtex abstract

   ×

   Rydberg-like image potential states (IPSs) form special series surface states on metal and semiconducting surfaces. Here, using time-resolved and momentum-resolved multi-photon photoemission (mPPE), we measured the energy positions, band dispersion, and carrier lifetimes of IPSs at the 2H-MoS2 surface. The energy minima of the IPSs (n = 1 and 2) were located at 0.77 and 0.21 eV below the vacuum level. In addition, the effective masses of these two IPSs are close to the rest mass of the free electron, clearly showing nearly-free-electron character. These properties suggest a good screening effect in the MoS2 parallel to the surface. The multi-photon resonances between the valence band and IPS (n = 1) are observed, showing a k‖-momentum-dependent behavior. Our time-resolved mPPE measurements show that the lifetime of photoexcited electrons in the IPS (n = 1) is about 33 fs.

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   ×

   @article{Liu_PCCP_2021,
     author = {Liu, Jianyi and Jiang, Xiang and Li, Xintong and Ma, Xiaochuan and Sun, Xia and Zheng, Qijing and Cui, Xuefeng and Tan, Shijing and Zhao, Jin and Wang, Bing},
     doi = {10.1039/D1CP03527D},
     issn = {1463-9076},
     journal = {Physical Chemistry Chemical Physics},
     corresponding_authors = {Zhao Jin, Cui Xuefeng, Wang Bing},
     number = {46},
     pages = {26336--26342},
     title = {{Time- and Momentum-resolved Image-potential States of 2H-MoS2 Surface}},
     volume = {23},
     month = nov,
     year = {2021}
   }
    

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5. Bidirectional and Reversible Tuning of the Interlayer Spacing of Two-dimensional Materials
   Ding, Yiran^#; Zeng, Mengqi^#; Zheng, Qijing; Zhang, Jiaqian; Xu, Ding; Chen, Weiyin; Wang, Chenyang; Chen, Shulin; Xie, Yingying; Ding, Yu; Zheng, Shuting; Zhao, Jin; Gao, Peng; Fu, Lei*
   Nature Communications, 12, 5886 (2021)
   Published: Oct, 2021
   Link bibtex abstract

   ×

   Interlayer spacing is expected to influence the properties of multilayer two-dimensional (2D) materials. However, the ability to non-destructively regulate the interlayer spacing bidirectionally and reversibly is challenging. Here we report the preparation of 2D materials with tunable interlayer spacing by introducing active sites (Ce ions) in 2D materials to capture and immobilize Pt single atoms. The strong chemical interaction between active sites and Pt atoms contributes to the intercalation behavior of Pt atoms in the interlayer of 2D materials and further promotes the formation of chemical bonding between Pt atom and host materials. Taking cerium-embedded molybdenum disulfide (MoS 2 ) as an example, intercalation of Pt atoms enables interlayer distance tuning via an electrochemical protocol, leading to interlayer spacing reversible and linear compression and expansion from 6.546 ± 0.039 Å to 5.792 ± 0.038 Å (\sim11 %). The electronic property evolution with the interlayer spacing variation is demonstrated by the photoluminescence (PL) spectra, delivering that the well-defined barrier between the multilayer and monolayer layered materials can be artificially designed.

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   ×

   @article{Ding2021,
     author = {Ding, Yiran and Zeng, Mengqi and Zheng, Qijing and Zhang, Jiaqian and Xu, Ding and Chen, Weiyin and Wang, Chenyang and Chen, Shulin and Xie, Yingying and Ding, Yu and Zheng, Shuting and Zhao, Jin and Gao, Peng and Fu, Lei},
     corresponding_authors = {Fu Lei},
     first_authors = {Ding Yiran, Zeng Mengqi},
     doi = {10.1038/s41467-021-26139-5},
     issn = {2041-1723},
     journal = {Nature Communications},
     month = oct,
     number = {1},
     pages = {5886},
     title = {{Bidirectional and Reversible Tuning of the Interlayer Spacing of Two-dimensional Materials}},
     url = {https://doi.org/10.1038/s41467-021-26139-5 https://www.nature.com/articles/s41467-021-26139-5},
     volume = {12},
     year = {2021}
   }
    

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6. Investigation of ab initio Nonadiabatic Molecular Dynamics of Excited Carriers in Condensed Matter Systems
   Zheng, Zhenfa^#; Jiang, Xiang; Chu, Weibin; Zhang, Lili; Guo, Hongli; Zhao, Chuanyu; Wang, Yanan; Wang, Aolei; Zheng, Qijing*; Zhao, Jin*
   Acta Physica Sinica, 70, 177101 (2021)
   Published: Sep, 2021
   Link bibtex abstract

   ×

   激发态动力学是凝聚态物理中至关重要且富有挑战的科学问题, 不仅需要从时间、空间、能量和动量等多个维度来描述, 同时还需要考虑各种准粒子的相互作用以及多体效应. 本文聚焦凝聚态体系激发态动力学的理论和应用研究, 结合含时密度泛函、GW-BSE与面跳跃方法, 发展了激发态动力学第一性原理计算软件Hefei-NAMD, 构建了可以同时从时间、空间、动量、能量、自旋等多个维度研究凝聚态体系激发态动力学的理论和程序框架, 并实现了自旋分辨的GW+ real-time BSE(GW+rtBSE)激子动力学. 利用这套方法, 研究了凝聚态体系激发态动力学的许多问题, 包括界面电荷转移动力学、电子空穴复合动力学以及二维TMD材料的谷激子动力学等. 这些研究从第一性原理计算的角度, 模拟激发态载流子在实空间、能量空间和动量空间的含时演化, 为凝聚态体系的激发态动力学及准粒子耦合过程提供了深刻细致的理解.

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   ×

   @article{ZhengZhenfa2021,
     author = {Zheng, Zhenfa and Jiang, Xiang and Chu, Weibin and Zhang, Lili and Guo, Hongli and Zhao, Chuanyu and Wang, Yanan and Wang, Aolei and Zheng, Qijing and Zhao, Jin},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     doi = {10.7498/aps.70.20210626},
     issn = {1000-3290},
     journal = {Acta Physica Sinica},
     number = {17},
     pages = {177101},
     title = {{Investigation of ab initio Nonadiabatic Molecular Dynamics of Excited Carriers in Condensed Matter Systems}},
     url = {http://wulixb.iphy.ac.cn/article/doi/10.7498/aps.70.20210626},
     volume = {70},
     year = {2021},
     month = sep
   }
    

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7. Patterning of Transition Metal Dichalcogenides Catalyzed by Surface Plasmons with Atomic Precision
   Zhou, Xiaoli^#; Hao, He; Zhang, Ying-Jie; Zheng, Qijing; Tan, Shijing*; Zhao, Jin; Chen, Hai-Bo; Chen, Jie-Jie; Gu, Ying*; Yu, Han-Qing; Liu, Xian-Wei*
   Chem, 7, 1626-1638 (2021)
   Published: Jun, 2021
   Link bibtex abstract

   ×

   Summary Plasmon-induced charge transfer has drawn considerable interests and spurred rapid developments of photovoltaics and photocatalysis. Various plasmonic metal/transition metal dichalcogenide (TMD) heterostructures have been developed to promote charge separation. For plasmon-induced catalysis, the transformation of TMDs is rare, and the erosion of TMDs has not yet been reported. Here, we report the etching of two-dimensional TMDs by planar surface plasmon polaritons (SPPs). We found that SPPs can etch various TMDs into desired layers and lateral size through controlling the light power and incident direction. In aqueous media, the strong plasmonic coupling at Au/MoS2 interface generates holes in the valence band of MoS2 that can weaken its interlayer interaction. As a synergistic effect, the plasmonic hot electrons produce oxidizing H2O2 to dissolve MoS2 from the top layers. Our results provide a new perspective for understanding the plasmonic coupling at metal-TMD interfaces and a reliable route toward fabricating well-defined TMDs.

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   ×

   @article{ZHOU2021,
     title = {Patterning of Transition Metal Dichalcogenides Catalyzed by Surface Plasmons with Atomic Precision},
     journal = {Chem},
     year = {2021},
     issn = {24519294},
     doi = {10.1016/j.chempr.2021.03.011},
     url = {https://www.sciencedirect.com/science/article/pii/S2451929421001613},
     author = {Zhou, Xiaoli and Hao, He and Zhang, Ying-Jie and Zheng, Qijing and Tan, Shijing and Zhao, Jin and Chen, Hai-Bo and Chen, Jie-Jie and Gu, Ying and Yu, Han-Qing and Liu, Xian-Wei},
     corresponding_authors = {Tan Shijing, Gu Ying, Liu Xian-Wei},
     keywords = {surface plasmon, transition metal dichalcogenide, catalysis, etching, hot electrons},
     month = jun,
     volume = {7},
     number = {6},
     pages = {1626-1638}
   }
    

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8. Strong Modulation of Band Gap, Carrier Mobility and Lifetime in Two-Dimensional Black Phosphorene through Acoustic Phonon Excitation
   Guo, Hongli^#; Chu, Weibin; Prezhdo, Oleg V; Zheng, Qijing*; Zhao, Jin
   Journal of Physical Chemistry Letters, 12, 3960–3967 (2021)
   Published: Apr, 2021
   Link bibtex abstract

   ×

   Black phosphorene (BP) has been attracting intense attention due to its high charge mobility and potential applications in electronic, optical and optoelectronic devices. We demonstrate by ab initio molecular dynamics and nonadiabatic quantum dynamics simulations that the excitation of out-of-plane acoustic phonon (ZA) provides strong modulation of the band gap, carrier lifetime and carrier mobility in BP. A 1% tensile strain can significantly enhance ZA mode excitation at room temperature, distinctly reducing the band gap, carrier mobility, and lifetime. These electronic properties can be tuned easily by influencing the excitation amplitude of the ZA mode. Unique to the family of two-dimensional materials, the ZA mode plays an essential role in controlling the electronic properties of BP. The results of our study provide valuable guidelines for design of functional nanodevices based on 2D BP.

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   ×

   @article{Guo2021,
     annote = {doi: 10.1021/acs.jpclett.1c00747},
     author = {Guo, Hongli and Chu, Weibin and Prezhdo, Oleg V and Zheng, Qijing and Zhao, Jin},
     doi = {10.1021/acs.jpclett.1c00747},
     issn = {1948-7185},
     journal = {Journal of Physical Chemistry Letters},
     month = apr,
     volume = {12},
     number = {16},
     pages = {3960--3967},
     publisher = {American Chemical Society},
     corresponding_authors = {Zheng Qijing},
     title = {{Strong Modulation of Band Gap, Carrier Mobility and Lifetime in Two-Dimensional Black Phosphorene through Acoustic Phonon Excitation}},
     url = {https://doi.org/10.1021/acs.jpclett.1c00747 https://pubs.acs.org/doi/10.1021/acs.jpclett.1c00747},
     year = {2021}
   }
    

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9. Real-Time GW-BSE Investigations on Spin-Valley Exciton Dynamics in Monolayer Transition Metal Dichalcogenide
   Jiang, Xiang^#; Zheng, Qijing; Lan, Zhenggang; Saidi, Wissam A; Ren, Xinguo; Zhao, Jin*
   Science Advances, 7, eabf3759 (2021)
   Published: Mar, 2021
   Link bibtex abstract PDF

   ×

   We develop an ab initio nonadiabatic molecular dynamics (NAMD) method based on GW plus real-time Bethe-Salpeter equation (GW + rtBSE-NAMD) for the spin-resolved exciton dynamics. From investigations on MoS2 , we provide a comprehensive picture of spin-valley exciton dynamics where the electron-phonon (e-ph) scattering, spin-orbit interaction (SOI), and electron-hole (e-h) interactions come into play collectively. In particular, we provide a direct evidence that e-h exchange interaction plays a dominant role in the fast valley depolarization within a few picoseconds, which is in excellent agreement with experiments. Moreover, there are bright-to-dark exciton transitions induced by e-ph scattering and SOI. Our study proves that e-h many-body effects are essential to understand the spin-valley exciton dynamics in transition metal dichalcogenides and the newly developed GW + rtBSE-NAMD method provides a powerful tool for exciton dynamics in extended systems with time, space, momentum, energy, and spin resolution.

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   ×

   @article{JiangX2021,
     corresponding_authors = {Zhao Jin},
     author = {Jiang, Xiang and Zheng, Qijing and Lan, Zhenggang and Saidi, Wissam A and Ren, Xinguo and Zhao, Jin},
     doi = {10.1126/sciadv.abf3759},
     issn = {2375-2548},
     journal = {Science Advances},
     mendeley-groups = {2020_mianshang/m2},
     month = mar,
     number = {10},
     pages = {eabf3759},
     title = {{Real-Time GW-BSE Investigations on Spin-Valley Exciton Dynamics in Monolayer Transition Metal Dichalcogenide}},
     url = {https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abf3759},
     pdf = {/assets/pdf/pubs/JiangXiang_SciAdv_2021.pdf},
     volume = {7},
     year = {2021}
   }
    

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10. Dynamics of Photoexcited Small Polarons in Transition-Metal Oxides
    Zhang, Lili^#; Chu, Weibin; Zhao, Chuanyu; Zheng, Qijing*; Prezhdo, Oleg V; Zhao, Jin
    Journal of Physical Chemistry Letters, 12, 2191–2198 (2021)
    Published: Feb, 2021
    Link bibtex abstract

    ×

    The dynamics of photoexcited polarons in transition-metal oxides (TMOs), including their formation, migration, and quenching, plays an important role in photocatalysis and photovoltaics. Taking rutile TiO2 as a prototypical system, we use ab initio nonadiabatic molecular dynamics simulation to investigate the dynamics of small polarons induced by photoexcitation at different temperatures. The photoexcited electron is trapped by the distortion of the surrounding lattice and forms a small polaron within tens of femtoseconds. Polaron migration among Ti atoms is strongly correlated with quenching through an electron–hole (e–h) recombination process. At low temperature, the polaron is localized on a single Ti atom and polaron quenching occurs within several nanoseconds. At increased temperature, as under solar cell operating conditions, thermal phonon excitation stimulates the hopping and delocalization of polarons, which induces fast polaron quenching through the e–h recombination within 200 ps. Our study proves that e–h recombination centers can be formed by photoexcited polarons, which provides new insights to understand the efficiency bottleneck of photocatalysis and photovoltaics in TMOs.

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    ×

    @article{Zhang2021,
      annote = {doi: 10.1021/acs.jpclett.1c00003},
      author = {Zhang, Lili and Chu, Weibin and Zhao, Chuanyu and Zheng, Qijing and Prezhdo, Oleg V and Zhao, Jin},
      corresponding_authors = {Zheng Qijing},
      doi = {10.1021/acs.jpclett.1c00003},
      issn = {1948-7185},
      journal = {Journal of Physical Chemistry Letters},
      month = feb,
      volume = {12},
      number = {9},
      pages = {2191--2198},
      publisher = {American Chemical Society},
      title = {{Dynamics of Photoexcited Small Polarons in Transition-Metal Oxides}},
      url = {https://doi.org/10.1021/acs.jpclett.1c00003 https://pubs.acs.org/doi/10.1021/acs.jpclett.1c00003},
      year = {2021}
    }
     

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2020

1. Interfacial Hydrogen-Bonding Dynamics in Surface-Facilitated Dehydrogenation of Water on TiO₂(110)
   Tan, Shijing^#; Feng, Hao; Zheng, Qijing; Cui, Xuefeng; Zhao, Jin; Luo, Yi; Yang, Jinlong; Wang, Bing*; Hou, J. G.*
   Journal of the American Chemical Society, 142, 826–834 (2020)
   Published: Dec, 2020
   Link bibtex abstract

   ×

   Molecular-level understanding of the dehydrogenation of interfacial water molecules on metal oxides and their interactive nature relies on the ability to track the motion of light and small hydrogen atoms, which is known to be difficult. Here, we report precise measurements of the surface-facilitated water dehydrogenation process at terminal Ti sites of TiO2(110) using scanning tunneling microscopy. Our measured hydrogen-bond dynamics of H2O and D2O reveal that the vibrational and electronic excitations dominate the sequential transfer of two H (D) atoms from a H2O (D2O) molecule to adjacent surface oxygen sites, manifesting the active participation of the oxide surface in the dehydrogenation processes. Our results show that, at the stoichiometric Ti5c sites, individual H2O molecules are energetically less stable than the dissociative form, where a barrier is expected to be as small as approximately 70-120 meV on the basis of our experimental and theoretical results. Moreover, our results reveal that interfacial hydrogen bonds can effectively assist H atom transfer and exchange across the surface. The revealed quantitative hydrogen-bond dynamics provide a new atomistic mechanism for water interactions on metal oxides in general.

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   ×

   @article{tan2020interfacial,
     author = {Tan, Shijing and Feng, Hao and Zheng, Qijing and Cui, Xuefeng and Zhao, Jin and Luo, Yi and Yang, Jinlong and Wang, Bing and Hou, J. G.},
     corresponding_authors = {Wang Bing, Hou J. G.},
     doi = {10.1021/jacs.9b09132},
     issn = {15205126},
     journal = {Journal of the American Chemical Society},
     number = {2},
     pages = {826--834},
     pmid = {31842546},
     publisher = {American Chemical Society},
     month = dec,
     title = {{Interfacial Hydrogen-Bonding Dynamics in Surface-Facilitated Dehydrogenation of Water on TiO2(110)}},
     volume = {142},
     year = {2020}
   }
    

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2. Accurate Computation of Nonadiabatic Coupling With Projector Augmented-Wave Pseudopotentials
   Chu, Weibin^#; Zheng, Qijing; Akimov, Alexey V.*; Zhao, Jin*; Saidi, Wissam A.*; Prezhdo, Oleg V.*
   Journal of Physical Chemistry Letters, 11, 10073–10080 (2020)
   Published: Nov, 2020
   Link bibtex abstract

   ×

   Synergy of nonadiabatic molecular dynamics with real-time time-dependent density functional theory has led to significant progress in modeling excited-state dynamics in nanoscale and condensed matter systems over the past decade. Nonadiabatic coupling (NAC) is the central quantity in such simulations, and its accurate and efficient evaluation is an enduring challenge in time-dependent Kohn-Sham theory, particularly in conjunction with planewave basis sets and projector augmented-wave (PAW) pseudopotentials because of the complexity of the PAW "all-electron"wave function. We report a method for rigorous evaluation of the NAC with PAW wave functions and demonstrate an efficient approximation to the rigorous NAC that gives comparable accuracy. As a validation, we intensely examine the NAC matrix elements calculated using both pseudo- and all-electron wave functions under the PAW formalism in six representative systems. The approximate NAC obtained with pseudowave functions is close to the exact all-electron NAC, with the largest deviations observed when subshell d-electrons are involved in the transitions. The developed approach provides a rigorous and convenient methodology for the numerical computation of NAC in the Kohn-Sham theory framework.

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   ×

   @article{chu2020accurate,
     author = {Chu, Weibin and Zheng, Qijing and Akimov, Alexey V. and Zhao, Jin and Saidi, Wissam A. and Prezhdo, Oleg V.},
     corresponding_authors = {Akimov Alexey V., Zhao Jin, Saidi Wissam A., Prezhdo Oleg V.},
     doi = {10.1021/acs.jpclett.0c03080},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     number = {23},
     pages = {10073--10080},
     pmid = {33179939},
     publisher = {ACS Publications},
     month = nov,
     title = {{Accurate Computation of Nonadiabatic Coupling With Projector Augmented-Wave Pseudopotentials}},
     volume = {11},
     year = {2020}
   }
    

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3. Interlayer Polarization Explains Slow Charge Recombination in Two-Dimensional Halide Perovskites by Nonadiabatic Molecular Dynamics Simulation
   Su, Jianfeng^#; Zheng, Qijing; Shi, Yongliang*; Zhao, Jin*
   Journal of Physical Chemistry Letters, 11, 9032–9037 (2020)
   Published: Oct, 2020
   Link bibtex abstract

   ×

   Two-dimensional (2D) perovskites for applications in photovoltaics and optoelectronics are attracting a great deal of research interest. The nonradiative electron-hole (e-h) recombination is the major efficiency loss channel. Herein, we report a study of the thickness dependence of the e-h recombination dynamics in diamine-based 2D perovskite via ab initio NAMD. For multilayer structures, due to the emergence of spontaneous interlayer electric polarization, which is induced by the collective and correlated reorientation of methylammonium molecules, the electron and hole at the band edges are localized in different inorganic layers, suppressing the e-h recombination. Furthermore, a broad range of phonon excitation also inspired rapid pure dephasing related to the microscopic origin for longer recombination times. The combination of the two effects leads to the observation of a prolonged carrier lifetime in multilayer 2D perovskites, which is essential to understanding the nonradiative e-h recombination mechanism in such materials.

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   ×

   @article{su2020interlayer,
     author = {Su, Jianfeng and Zheng, Qijing and Shi, Yongliang and Zhao, Jin},
     month = oct,
     corresponding_authors = {Zhao Jin, Shi Yongliang},
     doi = {10.1021/acs.jpclett.0c02838},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     number = {21},
     pages = {9032--9037},
     pmid = {33044072},
     publisher = {American Chemical Society},
     title = {{Interlayer Polarization Explains Slow Charge Recombination in Two-Dimensional Halide Perovskites by Nonadiabatic Molecular Dynamics Simulation}},
     volume = {11},
     year = {2020}
   }
    

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4. Halogen Modified Two-Dimensional Covalent Triazine Frameworks as Visible-light Driven Photocatalysts for Overall Water Splitting
   Fu, Cen Feng^#; Zhao, Chuanyu; Zheng, Qijing; Li, Xingxing*; Zhao, Jin; Yang, Jinlong*
   Science China Chemistry, 63, 1134–1141 (2020)
   Published: Jun, 2020
   Link bibtex abstract

   ×

   The covalent triazine framework CTF-1 as a member of the two-dimensional covalent organic frameworks (COFs) is a category of novel metal-free photocatalysts for water splitting. The large band gap severely restricts its energy conversion efficiency. By means of the first-principles calculations, we proposed the decoration of CTF-1 by anchoring halogen atoms onto benzene moieties for improving the solar-to-hydrogen (STH) efficiency. The electronic structures reveal that the halogen substitution successfully decreases the band gap of CTF-1. Meanwhile, the calculated free energy changes along the reaction pathway indicate that all these COFs can spontaneously drive overall water splitting under light irradiation in a specific acid-base environment. The time-dependent ab initio non-adiabatic molecular dynamics simulations suggest that the electron-hole recombination periods of these COFs fall in a few to tens of nanoseconds. Excitingly, CTF-1 modified by linking six iodine atoms onto the benzene ring in the para-position (CTF-1-6I) shows a quite low band gap of 2.81 eV, indicating that it is a visible-light driven COF for overall photocatalytic water splitting. Correspondingly, CTF-1-6I also exhibits an extraordinarily promising STH efficiency of 3.70%, which is an order magnitude higher than that of the pristine CTF-1.

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   ×

   @article{fu2020halogen,
     author = {Fu, Cen Feng and Zhao, Chuanyu and Zheng, Qijing and Li, Xingxing and Zhao, Jin and Yang, Jinlong},
     corresponding_authors = {Li Xingxing, Yang Jinlong},
     doi = {10.1007/s11426-020-9766-5},
     issn = {18691870},
     journal = {Science China Chemistry},
     keywords = {covalent organic frameworks,first-principles calculations,halogen substitution,photocatalytic water splitting},
     number = {8},
     pages = {1134--1141},
     publisher = {Science China Press},
     month = jun,
     title = {{Halogen Modified Two-Dimensional Covalent Triazine Frameworks as Visible-light Driven Photocatalysts for Overall Water Splitting}},
     volume = {63},
     year = {2020}
   }
    

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5. Tuning the Carrier Lifetime in Black Phosphorene Through Family Atom Doping
   Guo, Hongli^#; Chu, Weibin; Zheng, Qijing*; Zhao, Jin*
   Journal of Physical Chemistry Letters, 11, 4662–4667 (2020)
   Published: May, 2020
   Link bibtex abstract

   ×

   It is highly desirable to control the carrier lifetime in two-dimensional (2D) materials to suit the needs of various device functionalities. In this work, by ab initio nonadiabatic molecular dynamics simulation, we find the single atom doping from phosphorus family elements can sufficiently tune the carrier lifetime in black phosphorene (BP). Instead of forming electron-hole (e-h) recombination centers, the e-h recombination is suppressed by doping compared with the pristine BP. Moreover, it is found the carrier lifetime has a strong correlation with the mass of the doping atoms. A doping atom with larger mass leads to a longer lifetime. With the heaviest family element Bi doping, the carrier lifetime increases from 0.29 to 5.34 ns. This trend can be understood from the reduction of the nuclear velocity due to the heavy doping atom. We propose this conclusion can be extended to other monoelemental 2D semiconductors, which provides important guidance for the future design of functional nanodevices.

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   ×

   @article{guo2020tuning,
     author = {Guo, Hongli and and Chu, Weibin and Zheng, Qijing and Zhao, Jin},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     doi = {10.1021/acs.jpclett.0c01300},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     number = {12},
     pages = {4662--4667},
     pmid = {32464063},
     publisher = {American Chemical Society},
     month = may,
     title = {{Tuning the Carrier Lifetime in Black Phosphorene Through Family Atom Doping}},
     volume = {11},
     year = {2020}
   }
    

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6. Low-Frequency Lattice Phonons in Halide Perovskites Explain High Defect Tolerance Toward Electron-Hole Recombination
   Chu, Weibin^#; Zheng, Qijing; Prezhdo, Oleg V.; Zhao, Jin*; Saidi, Wissam A.*
   Science Advances, 6, eaaw7453 (2020)
   Published: Feb, 2020
   Link bibtex abstract

   ×

   Low-cost solution-based synthesis of metal halide perovskites (MHPs) invariably introduces defects in the system, which could form Shockley-Read-Hall (SRH) electron-hole recombination centers detrimental to solar conversion efficiency. Here, we investigate the nonradiative recombination processes due to native point defects in methylammonium lead halide (MAPbI3) perovskites using ab initio nonadiabatic molecular dynamics within surface-hopping framework. Regardless of whether the defects introduce a shallow or deep band state, we find that charge recombination in MAPbI3 is not enhanced, contrary to predictions from SRH theory. We demonstrate that this strong tolerance against defects, and hence the breakdown of SRH, arises because the photogenerated carriers are only coupled with low-frequency phonons and electron and hole states overlap weakly. Both factors appreciably decrease the nonadiabatic coupling. We argue that the soft nature of the inorganic lattice with small bulk modulus is key for defect tolerance, and hence, the findings are general to other MHPs.

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   ×

   @article{chu2020low,
     archiveprefix = {arXiv},
     arxivid = {2004.12559},
     author = {Chu, Weibin and Zheng, Qijing and Prezhdo, Oleg V. and Zhao, Jin and Saidi, Wissam A.},
     corresponding_authors = {Zhao Jin, Saidi Wissam A.},
     doi = {10.1126/sciadv.aaw7453},
     eprint = {2004.12559},
     issn = {23752548},
     journal = {Science Advances},
     month = feb,
     number = {7},
     pages = {eaaw7453},
     pmid = {32110721},
     title = {{Low-Frequency Lattice Phonons in Halide Perovskites Explain High Defect Tolerance Toward Electron-Hole Recombination}},
     url = {https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aaw7453},
     volume = {6},
     year = {2020}
   }
    

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7. Tensile Strain-Controlled Photogenerated Carrier Dynamics at the van der Waals Heterostructure Interface
   Tian, Yunzhe^#; Zheng, Qijing*; Zhao, Jin*
   Journal of Physical Chemistry Letters, 11, 586–590 (2020)
   Published: Jan, 2020
   Link bibtex abstract

   ×

   Customizing the photogenerrted carrier dynamics would make the two-dimensional (2D) materials highly adaptable to various application scenarios. On the basis of time-domain ab initio nonadiabatic molecular dynamics simulation, we find that 4% tensile strain can suppress the electron transfer at the van der Waals heterostructure MoS2/WS2 interface. Our analysis shows that after the electron-hole pair is excited in the K valley in WS2 direct electron transfer from WS2@K to MoS2@K is very difficult because of the weak interlayer coupling in the K valley, and thus, it happens through the T valley as WS2@K-MoS2@T-MoS2@K. When the tensile strain is applied, the energy of WS2@K is decreased, resulting in the suppression of electron transfer. Our study suggests that tuning of the interlayer charge-transfer dynamics by external strain is possible, which provides valuable insights into the functional design of photonic devices based on 2D materials.

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   ×

   @article{tian2020tensile,
     author = {Tian, Yunzhe and Zheng, Qijing and Zhao, Jin},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     doi = {10.1021/acs.jpclett.9b03534},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     number = {3},
     pages = {586--590},
     pmid = {31903763},
     publisher = {American Chemical Society},
     month = jan,
     title = {{Tensile Strain-Controlled Photogenerated Carrier Dynamics at the van der Waals Heterostructure Interface}},
     volume = {11},
     year = {2020}
   }
    

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8. CO₂ Photoreduction on Metal Oxide Surface Is Driven by Transient Capture of Hot Electrons: Ab Initio Quantum Dynamics Simulation
   Chu, Weibin^#; Zheng, Qijing; Prezhdo, Oleg V.; Zhao, Jin*
   Journal of the American Chemical Society, 142, 3214–3221 (2020)
   Published: Jan, 2020
   Link bibtex abstract

   ×

   The most critical bottleneck in CO₂ photoreduction lies in the activation of CO₂ to form an anion radical, CO₂•-, or other intermediates by the photoexcited electrons, because CO₂ has a high-energy lowest unoccupied molecular orbital (LUMO). Taking rutile TiO2(110) as a prototypical surface, we use time-dependent ab initio nonadiabatic molecular dynamics simulations to reveal that the excitation of bending and antisymmetric stretching vibrations of CO₂ can sufficiently stabilize the CO₂ LUMO below the conduction band minimum, allowing it to trap photoexcited hot electrons and get reduced. Such vibrational excitations occur by formation of a transient CO₂•- adsorbed in an oxygen vacancy. CO₂ can trap the hot electrons for nearly 100 fs and dissociate to form CO within 30-40 fs after the trapping. We propose that the activation of the CO₂ bending and antisymmetric stretching vibrations driven by hot electrons applies to other CO₂ reduction photocatalysts and can be realized by different techniques and material design.

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   ×

   @article{chu2020co,
     author = {Chu, Weibin and Zheng, Qijing and Prezhdo, Oleg V. and Zhao, Jin},
     corresponding_authors = {Zhao Jin},
     doi = {10.1021/jacs.9b13280},
     issn = {15205126},
     journal = {Journal of the American Chemical Society},
     number = {6},
     month = jan,
     pages = {3214--3221},
     pmid = {31965798},
     publisher = {American Chemical Society},
     title = {{CO2 Photoreduction on Metal Oxide Surface Is Driven by Transient Capture of Hot Electrons: Ab Initio Quantum Dynamics Simulation}},
     volume = {142},
     year = {2020}
   }
    

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2019

1. Dynamics of Single-Molecule Dissociation by Selective Excitation of Molecular Phonons
   Chen, Caiyun^#; Kong, Longjuan^#; Wang, Yu; Cheng, Peng; Feng, Baojie; Zheng, Qijing; Zhao, Jin*; Chen, Lan*; Wu, Kehui
   Physical Review Letters, 123, 246804 (2019)
   Published: Dec, 2019
   Link bibtex abstract

   ×

   Breaking bonds selectively in molecules is vital in many chemistry reactions and custom nanoscale device fabrications. The scanning tunneling microscope (STM) has proved to be an ideal tool to initiate and view bond-selective chemistry at the single-molecule level, offering opportunities for the further study of the dynamics in single molecules on metal surfaces. We demonstrate Hâ"HS and Hâ"S bond breaking on Au(111) induced by tunneling electrons using low-temperature STM. An experimental study combined with theoretical calculations shows that the dissociation pathway is facilitated by vibrational excitations. Furthermore, the dissociation probabilities of the two different dissociation processes are bias dependent due to different inelastic-tunneling probabilities, and they are also closely linked to the lifetime of inelastic-tunneling electrons. Combined with time-dependent ab initio nonadiabatic molecular dynamics simulations, the dynamics of the injected electron and the phonon-excitation-induced molecule dissociation can be understood at the atomic scale, demonstrating the potential application of STM for the investigation of excited-state dynamics of single molecules on surfaces.

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   ×

   @article{chen2019dynamics,
     author = {Chen, Caiyun and Kong, Longjuan and Wang, Yu and Cheng, Peng and Feng, Baojie and Zheng, Qijing and Zhao, Jin and Chen, Lan and Wu, Kehui},
     corresponding_authors = {Zhao Jin, Chen Lan},
     first_authors = {Chen Caiyun, Kong Longjuan},
     doi = {10.1103/PhysRevLett.123.246804},
     month = dec,
     issn = {10797114},
     journal = {Physical Review Letters},
     number = {24},
     pages = {246804},
     pmid = {31922847},
     publisher = {APS},
     title = {{Dynamics of Single-Molecule Dissociation by Selective Excitation of Molecular Phonons}},
     volume = {123},
     year = {2019}
   }
    

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2. Diabatic Hamiltonian Construction in van der Waals Heterostructure Complexes
   Xie, Yu^#; Sun, Huijuan; Zheng, Qijing; Zhao, Jin; Ren, Hao*; Lan, Zhenggang*
   Journal of Materials Chemistry A, 7, 27484–27492 (2019)
   Published: Nov, 2019
   Link bibtex abstract

   ×

   A diabatization method is developed for the approximated description of the photoinduced charge separation/transfer processes in van der Waals (vdW) heterostructure complexes, and is based on the wavefunction projection approach using a plane wave basis set in the framework of the single-particle picture. We built a diabatic Hamiltonian to describe the interlayer photoinduced hole-transfer process of two-dimensional vdW MoS2/WS2 heterostructure complexes. The diabatic Hamiltonian gives the energies of the localized band states, located in the MoS2 and WS2 layers, respectively, as well as the diabatic couplings between them. The wavefunction projection method provides a practical and reasonable approach to construct a diabatic model to describe the photoinduced charge transfer processes in the vdW heterostructure complexes.

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   ×

   @article{xie2019diabatic,
     author = {Xie, Yu and Sun, Huijuan and Zheng, Qijing and Zhao, Jin and Ren, Hao and Lan, Zhenggang},
     doi = {10.1039/c9ta09434b},
     issn = {20507496},
     journal = {Journal of Materials Chemistry A},
     number = {48},
     pages = {27484--27492},
     publisher = {Royal Society of Chemistry},
     month = nov,
     title = {{Diabatic Hamiltonian Construction in van der Waals Heterostructure Complexes}},
     corresponding_authors = {Lan Zhenggang, Ren Hao},
     url = {http://xlink.rsc.org/?DOI=C9TA09434B},
     volume = {7},
     year = {2019}
   }
    

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3. Ultrafast Electron Transfer Dynamics in Lateral Transition-Metal Dichalcogenide Heterostructures
   Zheng, Zhenfa^#; Zheng, Qijing*; Zhao, Jin*
   Electronic Structure, 1, 034001 (2019)
   Published: Sep, 2019
   Link bibtex abstract

   ×

   The ultrafast charge transfer in vertically stacked van der Waals transition-metal dichalcogenide (TMD) heterostructures shows enormous value in the fields of optoelectronics and solar energy conversion. Compared to vertical TMD heterostructures, the lateral (in-plane) heterostructures have stronger interaction between different TMD materials due to the formation of covalent bonds, which is more conducive to charge transfer. To understand the charge transfer dynamics in lateral TMD heterostructure, we employ ab initio nonadiabatic molecule dynamics to simulate the photoexcited electron transfer in lateral MoS2/WS2 heterostructure. Our study shows that the type-II band alignment can be formed in MoS2/WS2 at zero temperature. However, because the band offset of valence band maximum (VBM) is as small as 0.1 eV, the VBM of MoS2 and WS2 cross each other frequently when the temperature is increased to 100 or 300 K. In these cases, the phonon excitation destroys the type-II band alignment and makes the hole transfer to be difficult. By contrast, the band offset of conduction band minimum is kept with phonon excitation and our investigation shows that the electron transfer can happen in an ultrafast manner and the dynamics are independent of the interface structures. Comparing with the vertical MoS2/WS2 heterostructure, the nonadiabatic electron transfer can happen faster in lateral heterostructure because of the stronger orbital hybridization. Our investigation on lateral MoS2/WS2 heterostructures provide unique insights into the ultrafast charge transfer dynamics at lateral TMD interface at atomic scale, which have potential applications for the design of novel 2D devices for optoelectronics and clean energy.

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   ×

   @article{zheng2019ultrafast,
     author = {Zheng, Zhenfa and Zheng, Qijing and Zhao, Jin},
     doi = {10.1088/2516-1075/ab3b28},
     corresponding_authors = {Zhao Jin, Zheng Qijing},
     issn = {2516-1075},
     journal = {Electronic Structure},
     month = sep,
     number = {3},
     pages = {034001},
     publisher = {IOP Publishing},
     title = {{Ultrafast Electron Transfer Dynamics in Lateral Transition-Metal Dichalcogenide Heterostructures}},
     url = {https://iopscience.iop.org/article/10.1088/2516-1075/ab3b28},
     volume = {1},
     year = {2019}
   }
    

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4. Suppression of Electron-Hole Recombination by Intrinsic Defects in 2D Monoelemental Material
   Zhang, Lili^#; Chu, Weibin; Zheng, Qijing; Benderskii, Alexander V.; Prezhdo, Oleg V.*; Zhao, Jin*
   Journal of Physical Chemistry Letters, 10, 6151–6158 (2019)
   Published: Sep, 2019
   Link bibtex abstract

   ×

   The Shockley-Read-Hall (SRH) model, in which the deep trap defect states in the band gap are proposed as nonradiative electron-hole (e-h) recombination centers, has been widely used to describe the nonradiative e-h recombination through the defects in semiconductor. By using the ab initio nonadiabatic molecular dynamics method, we find that the SRH model fails to describe the e-h recombination behavior for defects in 2D monoelemental material such as monolayer black phosphorus (BP). Through the investigation of three intrinsic defects with shallow and deep defect states in monolayer BP, it is found that, surprisingly, none of these defects significantly accelerates the e-h recombination. Further analysis shows that because monolayer BP is a monoelemental material, the distinct impurity phonon, which often induces fast e-h recombination, is not formed. Moreover, because of the flexibility of 2D material, the defects scatter the phonons present in pristine BP, generating multiple modes with lower frequencies compared with the pristine BP, which further suppresses the e-h recombination. We propose that the conclusion can be extended to other monoelemental 2D materials, which is important guidance for the future design of functional semiconductors.

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   ×

   @article{zhang2019suppression,
     author = {Zhang, Lili and Chu, Weibin and Zheng, Qijing and Benderskii, Alexander V. and Prezhdo, Oleg V. and Zhao, Jin},
     corresponding_authors = {Prezhdo Oleg V., Zhao Jin},
     doi = {10.1021/acs.jpclett.9b02620},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     number = {20},
     pages = {6151--6158},
     pmid = {31553184},
     publisher = {American Chemical Society},
     month = sep,
     title = {{Suppression of Electron-Hole Recombination by Intrinsic Defects in 2D Monoelemental Material}},
     volume = {10},
     year = {2019}
   }
    

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5. Tailoring Exciton Dynamics of Monolayer Transition Metal Dichalcogenides by Interfacial Electron-Phonon Coupling
   Nie, Zhonghui^#; Shi, Yongliang; Qin, Shuchao; Wang, Yuhan; Jiang, Hongzhu; Zheng, Qijing; Cui, Yang; Meng, Yuze; Song, Fengqi; Wang, Xiaoyong; Turcu, Ion C.E.; Wang, Xinran; Xu, Yongbing; Shi, Yi; Zhao, Jin*; Zhang, Rong*; Wang, Fengqiu*
   Communications Physics, 2, 103 (2019)
   Published: Sep, 2019
   Link bibtex abstract

   ×

   With their strong light-matter interaction and rich photo-physics, two-dimensional (2D) transition metal dichalcogenides (TMDs) are important candidates for novel photonic and spin-valleytronic devices. It is highly desirable to control the photocarrier behaviours of monolayer TMDs to suit the needs of device functionalities. Here, through interfacial engineering, i.e., by depositing monolayer MoSe2 onto different oxide substrates (SiO2, Al2O3 and HfO2), we have revealed large tuning of the exciton relaxation times in monolayer TMDs. Significantly, the non-radiative recombination of MoSe2 is found shortened by almost one order of magnitude, from 160 ± 10 ps (on SiO2) to 20 ± 4 ps (on HfO2). Theoretical simulations based on ab initio non-adiabatic molecular dynamics (NAMD) method, together with temperature-dependent optical spectroscopy, identifies interfacial electron-phonon (e-ph) coupling as the leading mechanism for the lifetime tuning. Our results establish interface engineering as an effective knob for manipulating excited-state dynamics of monolayer TMDs.

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   ×

   @article{nie2019tailoring,
     author = {Nie, Zhonghui and Shi, Yongliang and Qin, Shuchao and Wang, Yuhan and Jiang, Hongzhu and Zheng, Qijing and Cui, Yang and Meng, Yuze and Song, Fengqi and Wang, Xiaoyong and Turcu, Ion C.E. and Wang, Xinran and Xu, Yongbing and Shi, Yi and Zhao, Jin and Zhang, Rong and Wang, Fengqiu},
     doi = {10.1038/s42005-019-0202-0},
     file = {:home/zqj/.local/share/data/Mendeley Ltd./Mendeley Desktop/Downloaded/Nie et al. - 2019 - Tailoring exciton dynamics of monolayer transition metal dichalcogenides by interfacial electron-phonon coupling.pdf:pdf},
     issn = {23993650},
     journal = {Communications Physics},
     number = {1},
     pages = {103},
     publisher = {Nature Publishing Group},
     month = sep,
     title = {{Tailoring Exciton Dynamics of Monolayer Transition Metal Dichalcogenides by Interfacial Electron-Phonon Coupling}},
     corresponding_authors = {Wang Fengqiu, Zhang Rong, Zhao Jin},
     volume = {2},
     year = {2019}
   }
    

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6. Photogenerated Carrier Dynamics at the Anatase/Rutile TiO₂ Interface
   Wang, Yanan^#; Shi, Yongliang; Zhao, Chuanyu; Zheng, Qijing*; Zhao, Jin*
   Physical Review B, 99, 165309 (2019)
   Published: Apr, 2019
   Link bibtex abstract

   ×

   TiO2 is an intensively studied photocatalytic material owing to its low cost and high activity. The anatase/rutile (A/R) mixed-phase TiO2 is recognized as an effective strategy to achieve high photocatalytic efficiency by the type-II band alignment favorable to spatial charge separation. However, the atomic structure, as well as the exact band alignment of the A/R mixed-phase TiO2, is very difficult to identify either in experimental measurements or theoretical simulations. Moreover, the time-dependent photogenerated carrier dynamics, which can determine the photocatalytic efficiency, has not been studied at the atomic scale. In this paper, we use an adaptive genetic algorithm to search the stable interface structures. We find that the band alignment is determined by the interfacial atomic structures. Especially, with oxygen vacancy (OV) at the interface, band alignment can be reversed as compared to that of the stoichiometric interface. Then, we select one stoichiometric and one defective structure to study the photogenerated carrier dynamics using the time-dependent ab initio nonadiabatic molecule dynamics. We find that in the stoichiometric system, for both the electron and the hole, the charge transfer happens within 400 fs, which is much shorter than the electron-hole recombination timescale at nanosecond-to-microsecond magnitude, which suggests that the charge transfer can occur efficiently at the interface before they recombine. For the defective A/R system with OV, we find that the electron will be trapped by the defect state within 1 ps, while the hole dynamics is not affected. Our study provides atomic insights into the understanding of the band alignment and photogenerated carrier dynamics at the mixed A/R TiO2 interface, which provides valuable guidance for functional material design for solar energy conversion.

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   ×

   @article{wang2019photogenerated,
     author = {Wang, Yanan and Shi, Yongliang and Zhao, Chuanyu and Zheng, Qijing and Zhao, Jin},
     doi = {10.1103/PhysRevB.99.165309},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     issn = {24699969},
     journal = {Physical Review B},
     number = {16},
     pages = {165309},
     publisher = {American Physical Society},
     month = apr,
     title = {{Photogenerated Carrier Dynamics at the Anatase/Rutile TiO2 Interface}},
     volume = {99},
     year = {2019}
   }
    

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7. Ab Initio Nonadiabatic Molecular Dynamics Investigations on the Excited Carriers in Condensed Matter Systems
   Zheng, Qijing^#; Chu, Weibin; Zhao, Chuanyu; Zhang, Lili; Guo, Hongli; Wang, Yanan; Jiang, Xiang; Zhao, Jin*
   Wiley Interdisciplinary Reviews: Computational Molecular Science, 9, e1411 (2019)
   Published: Mar, 2019
   Link bibtex abstract PDF

   ×

   The ultrafast dynamics of photoexcited charge carriers in condensed matter systems play an important role in optoelectronics and solar energy conversion. Yet it is challenging to understand such multidimensional dynamics at the atomic scale. Combining the real-time time-dependent density functional theory with fewest-switches surface hopping scheme, we develop time-dependent ab initio nonadiabatic molecular dynamics (NAMD) code Hefei-NAMD to simulate the excited carrier dynamics in condensed matter systems. Using this method, we have investigated the interfacial charge transfer dynamics, the electron–hole recombination dynamics, and the excited spin-polarized hole dynamics in different condensed matter systems. The time-dependent dynamics of excited carriers are studied in energy, real and momentum spaces. In addition, the coupling of the excited carriers with phonons, defects and molecular adsorptions are investigated. The state-of-art NAMD studies provide unique insights to understand the ultrafast dynamics of the excited carriers in different condensed matter systems at the atomic scale. This article is categorized under: Structure and Mechanism > Computational Materials Science Molecular and Statistical Mechanics > Molecular Dynamics and Monte-Carlo Methods Electronic Structure Theory > Ab Initio Electronic Structure Methods Software > Simulation Methods.

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   ×

   @article{zheng2019textit,
     author = {Zheng, Qijing and Chu, Weibin and Zhao, Chuanyu and Zhang, Lili and Guo, Hongli and Wang, Yanan and Jiang, Xiang and Zhao, Jin},
     doi = {10.1002/wcms.1411},
     issn = {17590884},
     journal = {Wiley Interdisciplinary Reviews: Computational Molecular Science},
     keywords = {Hefei-NAMD,excited carrier dynamics,nonadiabatic molecular dynamics,real-time time-dependent density functional theory},
     number = {6},
     pages = {e1411},
     publisher = {Wiley Periodicals, Inc.},
     corresponding_authors = {Zhao Jin},
     month = mar,
     title = {{Ab Initio Nonadiabatic Molecular Dynamics Investigations on the Excited Carriers in Condensed Matter Systems}},
     pdf = {/assets/pdf/pubs/ZhengQijing_WIRES_2018.pdf},
     volume = {9},
     year = {2019}
   }
    

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8. Ultrafast Dynamics of Solvated Electrons at Anatase TiO₂/H₂O Interface
   Sun, Huijuan^#; Zheng, Qijing*; Lu, Wencai; Zhao, Jin*
   Journal of Physics Condensed Matter, 31, 114004 (2019)
   Published: Jan, 2019
   Link bibtex abstract

   ×

   Solvated electrons are known to be the lowest energy charge transfer pathways at oxide/aqueous interface and the understanding of the electron transfer dynamics at the interface is fundamental for photochemical and photocatalytic processes. Taking anatase TiO 2 /H 2 O interface as a prototypical system, we perform time-dependent ab initio nonadiabatic molecular dynamics calculations to study the charge transfer dynamics of solvated electrons. For the static electronic properties, we find that the dangling H atoms can stabilize solvated electrons. A solvated electron band can be formed with one monolayer H 2 O adsorption. The energies of the solvated electron band minimum (SEBM) decrease when H 2 O adsorbs dissociatively. Moreover, the surface oxygen vacancies are also helpful for stabilizing the solvated electron band. For the dynamics behaviour, we find that the ultrafast charge transfer from SEBM to anatase TiO 2 (1 0 1) surface at 100 K is mainly contributed by nonadiabatic mechanism. Comparing with rutile TiO 2 (1 1 0) surface, the lifetime of solvated electron on anatase TiO 2 (1 0 1) surface is longer, suggesting a better photocatalytic properties. Our results provide essential insights into the understanding of the charge transfer dynamics and the possible photocatalytic mechanism at oxide/aqueous interface.

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   ×

   @article{sun2019ultrafast,
     author = {Sun, Huijuan and Zheng, Qijing and Lu, Wencai and Zhao, Jin},
     month = jan,
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     doi = {10.1088/1361-648X/aafcf6},
     issn = {1361648X},
     journal = {Journal of Physics Condensed Matter},
     keywords = {nonadiabatic molecular dynamics,oxide/aqueous interface,solvated electron},
     number = {11},
     pages = {114004},
     pmid = {30625440},
     publisher = {IOP Publishing},
     title = {{Ultrafast Dynamics of Solvated Electrons at Anatase TiO2/H2O Interface}},
     volume = {31},
     year = {2019}
   }
    

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9. Highly Efficient Photogenerated Electron Transfer at A Black Phosphorus/Indium Selenide Heterostructure Interface From Ultrafast Dynamics
   Niu, Xianghong^#; Li, Yunhai; Zhang, Yehui; Zheng, Qijing; Zhao, Jin*; Wang, Jinlan*
   Journal of Materials Chemistry C, 7, 1864–1870 (2019)
   Published: Jan, 2019
   Link bibtex abstract

   ×

   Constructing van der Waals (vdW) semiconductor heterostructures is a possible approach to optimize the optoelectronic properties, and understanding photogenerated charge carrier dynamics at vdW heterostructure interfaces is of crucial importance. By using time-dependent ab initio nonadiabatic molecular dynamics simulations, we study the dynamics of photogenerated electrons at a BP/InSe heterostructure interface and observethe highly efficient separation of photogenerated electron-hole pairs at the interface. Instead of direct tunneling, the ultrafast transfer of excited electrons is significantly promoted by an adiabatic mechanism related to thermally excited nuclear motions stemming from strong e-p coupling and phonon excitation, and a small energy difference of donor-acceptor states. The internal quantum efficiency for charge separation can reach up to 99.6% and improved optical absorption is also observed in this heterostructure, making the BP/InSe heterostructure a compelling optoelectronic material.

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   ×

   @article{niu2019highly,
     author = {Niu, Xianghong and Li, Yunhai and Zhang, Yehui and Zheng, Qijing and Zhao, Jin and Wang, Jinlan},
     doi = {10.1039/C8TC06208K},
     issn = {20507526},
     journal = {Journal of Materials Chemistry C},
     number = {7},
     pages = {1864--1870},
     publisher = {Royal Society of Chemistry},
     month = jan,
     title = {{Highly Efficient Photogenerated Electron Transfer at A Black Phosphorus/Indium Selenide Heterostructure Interface From Ultrafast Dynamics}},
     corresponding_authors = {Wang Jinlan, Zhao Jin},
     volume = {7},
     year = {2019}
   }
    

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2018

1. Visualizing Elementary Reactions of Methanol by Electrons and Holes on TiO₂(110) Surface
   Tan, Shijing^#; Feng, Hao^#; Ji, Yongfei^#; Zheng, Qijing; Shi, Yongliang; Zhao, Jin; Zhao, Aidi; Yang, Jinlong; Luo, Yi; Wang, Bing*; Hou, J. G.*
   Journal of Physical Chemistry C, 122, 28805–28814 (2018)
   Published: Nov, 2018
   Link bibtex abstract

   ×

   Direct visualization and comparison of the elementary reactions induced by electrons and holes are of importance for finding a way to conduct chemical reactions and reaction sequences in a controllable manner. As a semiconductor, TiO 2 provides a playground to perform the measurements, and moreover, the information can be useful for design of high-performance TiO 2 -based catalysts and photocatalysts. Here, we present our investigation on the elementary reactions of CH 3 OH on TiO 2 surface through visualization of specific elementary steps by highly controllable electron and hole injection using scanning tunneling microscopy. The distinct sequential routes and their kinetics, namely, breaking C-O and O-H bonds by electrons and breaking O-H and C-H bonds by holes, respectively, have been experimentally identified and well elucidated by density functional theory calculations. Our nonlocal h-injection experimental and theoretical results suggest that the delocalized holes in the TiO 2 substrate should be responsible for the temperature-dependent h-route reactions. The locally triggered e-route reaction is associated with the fact that the location of the unoccupied hybridization states is much higher than that of the conduction band onset. Our findings resolve the long-standing debate about the intermediate species and reaction mechanism in photocatalytic oxidation of CH 3 OH. Our proposed protocol offers a powerful means to study elementary reactions induced by electrons and holes on a semiconductor surface in general.

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   ×

   @article{tan2018visualizing,
     author = {Tan, Shijing and Feng, Hao and Ji, Yongfei and Zheng, Qijing and Shi, Yongliang and Zhao, Jin and Zhao, Aidi and Yang, Jinlong and Luo, Yi and Wang, Bing and Hou, J. G.},
     doi = {10.1021/acs.jpcc.8b09784},
     issn = {19327455},
     journal = {Journal of Physical Chemistry C},
     number = {50},
     pages = {28805--28814},
     publisher = {American Chemical Society},
     month = nov,
     title = {{Visualizing Elementary Reactions of Methanol by Electrons and Holes on TiO2(110) Surface}},
     corresponding_authors = {Wang Bing, Hou J. G.},
     first_authors = {Tan Shijing, Feng Hao, Ji Yongfei},
     volume = {122},
     year = {2018}
   }
    

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2. Direct Z-Scheme Water Splitting Photocatalyst Based on Two-dimensional van der Waals Heterostructures
   Zhang, Ruiqi^#; Zhang, Lili^#; Zheng, Qijing; Gao, Pengfei; Zhao, Jin*; Yang, Jinlong*
   Journal of Physical Chemistry Letters, 9, 5419–5424 (2018)
   Published: Sep, 2018
   Link bibtex abstract

   ×

   Mimicking the natural photosynthesis in plants, Z-scheme water splitting is a promising strategy to improve photocatalytic activity. Searching for the direct Z-scheme photocatalysts is urgent and the crucial factor for the photocatalytic efficiency is the photogenerated electron-hole (e-h) recombination rate at the interface of two photosystems. In this report, based on time-dependent ab initio nonadiabatic molecular dynamics (NAMD) investigation, we first report a two-dimensional (2D) metal-free van der Waals (vdW) heterostructure consisting of monolayer BCN and C2N as a promising candidate for direct Z-scheme photocatalysts for water splitting. It is shown that the time scale of e-h recombination of BCN/C2N is within 2 ps. Among such e-h recombination events, more than 85% are through the e-h recombination at the interface. NAMD simulations based on frozen phonon method prove that such an ultrafast interlayer e-h recombination is assisted by intralayer optical phonon modes and the interlayer shear phonon mode induced by vdW interaction. In these crucial phonon modes, the interlayer relative movements which are lacking in traditional heterostructures with strong interactions, yet exist generally in various 2D vdW heterostructures, are significant. Our results prove that the 2D vdW heterostructure family is convincing for a new type of direct Z-scheme photocatalysts searching.

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   ×

   @article{zhang2018direct,
     author = {Zhang, Ruiqi and Zhang, Lili and Zheng, Qijing and Gao, Pengfei and Zhao, Jin and Yang, Jinlong},
     doi = {10.1021/acs.jpclett.8b02369},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     number = {18},
     pages = {5419--5424},
     pmid = {30180588},
     publisher = {American Chemical Society},
     corresponding_authors = {Yang Jinlong, Zhao Jin},
     first_authors = {Zhang Lili},
     month = sep,
     title = {{Direct Z-Scheme Water Splitting Photocatalyst Based on Two-dimensional van der Waals Heterostructures}},
     volume = {9},
     year = {2018}
   }
    

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3. Tuning Solvated Electrons by Polar-Nonpolar Oxide Heterostructure
   Wang, Yanan^#; Guo, Hongli; Zheng, Qijing*; Saidi, Wissam A.; Zhao, Jin*
   Journal of Physical Chemistry Letters, 9, 3049–3056 (2018)
   Published: Jun, 2018
   Link bibtex abstract

   ×

   Solvated electron states at the oxide/aqueous interface represent the lowest energy charge-transfer pathways, thereby playing an important role in photocatalysis and electronic device applications. However, their energies are usually higher than the conduction band minimum (CBM), which makes the solvated electrons difficult to utilize in charge-transfer processes. Thus it is essential to stabilize the energy of the solvated electron states. Taking LaAlO3/SrTiO3 (LAO/STO) oxide heterostructure with H2O-adsorbed monolayer as a prototypical system, we show using DFT and ab initio time-dependent nonadiabatic molecular dynamics simulation that the energy and dynamics of solvated electrons can be tuned by the electric field in the polar-nonpolar oxide heterostructure. In particular, for LAO/STO with p-type interface, the CBM is contributed by the solvated electron state when LAO is thicker than four unit cells. Furthermore, the solvated electron band minimum can be partially occupied when LAO is thicker than eight unit cells. We propose that the tunability of solvated electron states can be achieved on polar-nonpolar oxide heterostructure surfaces as well as on ferroelectric oxides, which is important for charge and proton transfer at oxide/aqueous interfaces.

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   ×

   @article{wang2018tuning,
     author = {Wang, Yanan and Guo, Hongli and Zheng, Qijing and Saidi, Wissam A. and Zhao, Jin},
     doi = {10.1021/acs.jpclett.8b00938},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     month = jun,
     number = {11},
     pages = {3049--3056},
     pmid = {29767527},
     publisher = {American Chemical Society},
     title = {{Tuning Solvated Electrons by Polar-Nonpolar Oxide Heterostructure}},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     url = {http://pubs.acs.org/doi/10.1021/acs.jpclett.8b00938},
     volume = {9},
     year = {2018}
   }
    

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4. Superatom Molecular Orbital as An Interfacial Charge Separation State
   Guo, Hongli^#; Zhao, Chuanyu; Zheng, Qijing*; Lan, Zhenggang; Prezhdo, Oleg V.; Saidi, Wissam A.; Zhao, Jin*
   Journal of Physical Chemistry Letters, 9, 3485–3490 (2018)
   Published: Jun, 2018
   Link bibtex abstract

   ×

   Hot electron cooling by energy loss to heat through electron-phonon (e-ph) interaction is an important mechanism that can limit the efficiency of solar energy conversion. To avoid such energy loss, sufficient charge separation needs to be realized by extracting hot carriers from the photoconverter before they cool, which requires fast interfacial charge transfer and slow internal hot carrier relaxation. Using ab initio time-dependent nonadiabatic molecular dynamics and taking C60/MoS2 as a prototype system, we show that the superatom molecular orbitals (SAMOs) of fullerenes, which are bound by the central potential of the whole molecule induced by the charge screening, are ideal media for charge separation. The diffuse character of SAMOs results in extremely weak e-ph interaction and therefore acts as a "phonon bottleneck" for hot electron cooling. Furthermore, it also leads to significant hybridization with other atoms at the interface that induces fast charge transfer. The interfacial charge-transfer rate at the C60/MoS2 interface is found to be 2 orders of magnitude faster than the hot electron cooling from s-SAMO in C60. This conclusion is generally applicable for different carbon nanostructures that have SAMOs. The proposed SAMO-induced charge separation provides unique and essential insights into the material design and function for solar energy conversion.

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   ×

   @article{Guo2018,
     author = {Guo, Hongli and Zhao, Chuanyu and Zheng, Qijing and Lan, Zhenggang and Prezhdo, Oleg V. and Saidi, Wissam A. and Zhao, Jin},
     doi = {10.1021/acs.jpclett.8b01302},
     issn = {19487185},
     journal = {Journal of Physical Chemistry Letters},
     month = jun,
     number = {12},
     pages = {3485--3490},
     pmid = {29869887},
     title = {{Superatom Molecular Orbital as An Interfacial Charge Separation State}},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     url = {https://doi.org/10.1021/acs.jpclett.8b01302 http://pubs.acs.org/doi/10.1021/acs.jpclett.8b01302},
     volume = {9},
     year = {2018}
   }
    

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5. Phonon-Coupled Ultrafast Interlayer Charge Oscillation at van der Waals Heterostructure Interfaces
   Zheng, Qijing^#; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V.; Saidi, Wissam A.; Zhao, Jin*
   Physical Review B, 97, 205417 (2018)
   Published: May, 2018
   Link bibtex abstract PDF

   ×

   Van der Waals (vdW) heterostructures of transition-metal dichalcogenide (TMD) semiconductors are central not only for fundamental science, but also for electro- and optical-device technologies where the interfacial charge transfer is a key factor. Ultrafast interfacial charge dynamics has been intensively studied, however, the atomic scale insights into the effects of the electron-phonon (e-p) coupling are still lacking. In this paper, using time dependent ab initio nonadiabatic molecular dynamics, we study the ultrafast interfacial charge transfer dynamics of two different TMD heterostructures MoS2/WS2 and MoSe2/WSe2, which have similar band structures but different phonon frequencies. We found that MoSe2/WSe2 has softer phonon modes compared to MoS2/WS2, and thus phonon-coupled charge oscillation can be excited with sufficient phonon excitations at room temperature. In contrast, for MoS2/WS2, phonon-coupled interlayer charge oscillations are not easily excitable. Our study provides an atomic level understanding on how the phonon excitation and e-p coupling affect the interlayer charge transfer dynamics, which is valuable for both the fundamental understanding of ultrafast dynamics at vdW hetero-interfaces and the design of novel quasi-two-dimensional devices for optoelectronic and photovoltaic applications.

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   ×

   @article{zheng2018phonon,
     author = {Zheng, Qijing and Xie, Yu and Lan, Zhenggang and Prezhdo, Oleg V. and Saidi, Wissam A. and Zhao, Jin},
     doi = {10.1103/PhysRevB.97.205417},
     isbn = {2469-9950
   2469-9969},
     issn = {24699969},
     journal = {Physical Review B},
     month = may,
     number = {20},
     pages = {205417},
     publisher = {American Physical Society},
     title = {{Phonon-Coupled Ultrafast Interlayer Charge Oscillation at van der Waals Heterostructure Interfaces}},
     corresponding_authors = {Zhao Jin},
     pdf = {/assets/pdf/pubs/ZhengQijing_PRB_2018.pdf},
     url = {https://link.aps.org/doi/10.1103/PhysRevB.97.205417},
     volume = {97},
     year = {2018}
   }
    

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6. Delocalized Impurity Phonon Induced Electron-Hole Recombination in Doped Semiconductors
   Zhang, Lili^#; Zheng, Qijing^#; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V.; Saidi, Wissam A.; Zhao, Jin*
   Nano Letters, 18, 1592–1599 (2018)
   Published: Mar, 2018
   Link bibtex abstract PDF

   ×

   Semiconductor doping is often proposed as an effective route to improving the solar energy conversion efficiency by engineering the band gap; however, it may also introduce electron-hole (e-h) recombination centers, where the determining element for e-h recombination is still unclear. Taking doped TiO2 as a prototype system and by using time domain ab initio nonadiabatic molecular dynamics, we find that the localization of impurity-phonon modes (IPMs) is the key parameter to determine the e-h recombination time scale. Noncompensated charge doping introduces delocalized impurity-phonon modes that induce ultrafast e-h recombination within several picoseconds. However, the recombination can be largely suppressed using charge-compensated light-mass dopants due to the localization of their IPMs. For different doping systems, the e-h recombination time is shown to depend exponentially on the IPM localization. We propose that the observation that delocalized IPMs can induce fast e-h recombination is broadly applicable and can be used in the design and synthesis of functional semiconductors with optimal dopant control.

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   ×

   @article{zhang2018delocalized,
     author = {Zhang, Lili and Zheng, Qijing and Xie, Yu and Lan, Zhenggang and Prezhdo, Oleg V. and Saidi, Wissam A. and Zhao, Jin},
     doi = {10.1021/acs.nanolett.7b03933},
     issn = {15306992},
     journal = {Nano Letters},
     keywords = {Semiconductor doping,electron-hole recombination,impurity-phonon mode,nonadiabaic molecular dynamics},
     month = mar,
     number = {3},
     pages = {1592--1599},
     pmid = {29393653},
     publisher = {American Chemical Society},
     title = {{Delocalized Impurity Phonon Induced Electron-Hole Recombination in Doped Semiconductors}},
     pdf = {/assets/pdf/pubs/ZhangLili_NanoLett_2018.pdf},
     corresponding_authors = {Zhao Jin},
     first_authors = {Zheng Qijing},
     url = {http://pubs.acs.org/doi/10.1021/acs.nanolett.7b03933},
     volume = {18},
     year = {2018}
   }
    

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2017

1. Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface
   Zheng, Qijing^#; Saidi, Wissam A.; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V.; Petek, Hrvoje; Zhao, Jin*
   Nano Letters, 17, 6435–6442 (2017)
   Published: Oct, 2017
   Link bibtex abstract PDF

   ×

   The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary to general expectation, efficient electron-hole separation can occur in vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast charge transfer between the neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic molecular dynamics calculations, that instead of direct tunneling, the ultrafast interlayer hole transfer is strongly promoted by an adiabatic mechanism through phonon excitation occurring on 20 fs, which is in good agreement with the experiment. The atomic level picture of the phonon-assisted ultrafast mechanism revealed in our study is valuable both for the fundamental understanding of ultrafast charge carrier dynamics at vdW heterointerfaces as well as for the design of novel quasi-2D devices for optoelectronic and photovoltaic applications.

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   ×

   @article{zheng2017phonon,
     annote = {From Duplicate 1 (Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface - Zheng, Qijing; Saidi, Wissam A.; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V.; Petek, Hrvoje; Zhao, Jin)
     
     Petek, Hrvoje/A-3912-2009; Lan, Zhenggang/H-3676-2012; xie, yu/; Saidi, Wissam A./
     Petek, Hrvoje/0000-0001-9605-2590; xie, yu/0000-0001-8925-6958; Saidi, Wissam A./0000-0001-6714-4832
     1530-6992},
     author = {Zheng, Qijing and Saidi, Wissam A. and Xie, Yu and Lan, Zhenggang and Prezhdo, Oleg V. and Petek, Hrvoje and Zhao, Jin},
     corresponding_authors = {Zhao Jin},
     doi = {10.1021/acs.nanolett.7b03429},
     file = {:home/zqj/Downloads/acs.nanolett.7b03429.pdf:pdf},
     issn = {15306992},
     journal = {Nano Letters},
     keywords = {nonadiabatic molecular dynamics,ultrafast charge transfer,van der Waals heterointerface},
     month = oct,
     number = {10},
     pages = {6435--6442},
     pmid = {28914539},
     publisher = {American Chemical Society},
     title = {{Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface}},
     pdf = {/assets/pdf/pubs/ZhengQijing_NanoLett_2017.pdf},
     url = {https://pubs.acs.org/doi/10.1021/acs.nanolett.7b03429},
     volume = {17},
     year = {2017}
   }
    

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2. Ab Initio Nonadiabatic Molecular Dynamics Investigation on the Dynamics of Photogenerated Spin Hole Current in Cu-Doped MoS₂
   Zhao, Chuanyu^#; Zheng, Qijing*; Wu, Jianlan; Zhao, Jin*
   Physical Review B, 96, 134308 (2017)
   Published: Oct, 2017
   Link bibtex abstract

   ×

   Fully spin-polarized hole current is theoretically proposed to be generated by photoexcitation in the impurity states of the MoS2 monolayer with sulfur partially substituted by copper. To understand the dynamics of the photogenerated spin hole current, we perform a time-domain ab initio nonadiabatic molecular dynamics investigation with different initial excitation and temperature. First, the spin hole relaxes in a band-by-band manner. Therefore a longer lifetime can be achieved if the initial hole is generated at the lower edge of the impurity bands. Second, the phonon excitation is found to affect the spin hole dynamics significantly. When the temperature is decreased from 100 to 50 K, the hole relaxation across the band gap is strongly suppressed by the phonon bottleneck, which is due to the reduction of the phonon occupations. Our results show that the initial hole generation and phonon excitation are two key factors determining the dynamics of the photogenerated spin hole, which provide insights into the design of optimal spintronic devices.

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   ×

   @article{zhao2017textit,
     author = {Zhao, Chuanyu and Zheng, Qijing and Wu, Jianlan and Zhao, Jin},
     doi = {10.1103/PhysRevB.96.134308},
     issn = {24699969},
     journal = {Physical Review B},
     number = {13},
     pages = {134308},
     publisher = {American Physical Society},
     month = oct,
     title = {{Ab Initio Nonadiabatic Molecular Dynamics Investigation on the Dynamics of Photogenerated Spin Hole Current in Cu-Doped MoS2}},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     volume = {96},
     year = {2017}
   }
    

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2016

1. Ultrafast Dynamics of Photongenerated Holes at a CH₃OH/TiO₂ Rutile Interface
   Chu, Weibin^#; Saidi, Wissam A.; Zheng, Qijing*; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V.; Petek, Hrvoje; Zhao, Jin*
   Journal of the American Chemical Society, 138, 13740–13749 (2016)
   Published: Oct, 2016
   Link bibtex abstract PDF

   ×

   Photogenerated charge carrier dynamics near molecule/TiO2 interfaces are important for the photocatalytic and photovoltaic processes. To understand this fundamental aspect, we performed a time-domain ab initio nonadiabatic molecular dynamics study of the photogenerated hole dynamics at the CH3OH/rutile TiO2(110) interface. We studied the forward and reverse hole transfer between TiO2 and CH3OH as well as the hole energy relaxation to the valence band maximum. First, we show that the hole-trapping ability of CH3OH depends strongly on the adsorption structure. Only when the CH3OH is deprotonated to form chemisorbed CH3O will ∼15% of the hole be trapped by the molecule. Second, we find that strong fluctuations of the HOMO energies of the adsorbed molecules induced by electron-phonon coupling provide additional channels, which accelerate the hole energy relaxation. Third, we demonstrate that the charge transfer and energy relaxation processes depend significantly on temperature. When the temperature decreases from 100 to 30 K, the forward hole transfer and energy relaxation processes are strongly suppressed because of the reduction of phonon occupation. These results indicate that the molecule/TiO2 energy level alignment, thermal excitation of a phonon, and electron-phonon coupling are the key factors that determine the photogenerated hole dynamics. Our studies provide valuable insights into the photogenerated charge and energy transfer dynamics at molecule/semiconductor interfaces.

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   ×

   @article{chu2016ultrafast,
     author = {Chu, Weibin and Saidi, Wissam A. and Zheng, Qijing and Xie, Yu and Lan, Zhenggang and Prezhdo, Oleg V. and Petek, Hrvoje and Zhao, Jin},
     doi = {10.1021/jacs.6b08725},
     isbn = {1520-5126 (Electronic)
   0002-7863 (Linking)},
     issn = {15205126},
     journal = {Journal of the American Chemical Society},
     month = oct,
     number = {41},
     pages = {13740--13749},
     pmid = {27656768},
     publisher = {American Chemical Society},
     title = {{Ultrafast Dynamics of Photongenerated Holes at a CH3OH/TiO2 Rutile Interface}},
     corresponding_authors = {Zheng Qijing, Zhao Jin},
     url = {https://pubs.acs.org/doi/10.1021/jacs.6b08725},
     pdf = {/assets/pdf/pubs/ChuWeibin_JACS_2016.pdf},
     volume = {138},
     year = {2016}
   }
    

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2. Dynamic Equilibrium of Reversible Reactions and Migration of Hydrogen Atoms Mediated by Diffusive Methanol on Rutile TiO₂(110)-(1×1) Surface
   Zheng, Qijing^#; Tan, Shijing^#; Feng, Hao; Cui, Xuefeng*; Zhao, Jin; Wang, Bing*
   Journal of Physical Chemistry C, 120, 7728–7735 (2016)
   Published: Apr, 2016
   Link bibtex abstract

   ×

   We report our investigation of the reversible reaction of methanol and the migration of hydrogen adatom (Had) on TiO2(110)-(1 × 1) surface at various temperatures and methanol coverages using scanning tunneling microscopy joint with density functional theory (DFT) calculations. At a relatively low coverage measured at room temperature, the methanol species adsorbed at the oxygen vacancy (OV) sites are immobile and appear only as a dissociative form, and the observed Had migration events are very few. However, when the OV sites are fully filled by methanol in the methanol-overdosed sample, the methanol species at the OV sites keep immobile but frequently switch between molecular and dissociative forms, accompanied by dramatically enhanced Had migration. Meanwhile, an established equilibrium shows a concentration ratio of 1:3 between the molecular and dissociative methanol. At 235 K, we directly visualized and confirmed that the reversible reactions of methanol and the enhanced Had migration are mediated by the diffusive methanol adsorbed at the 5-fold coordinated Ti sites. Our DFT calculations well elucidate the experimental results using the modeled configurations by considering the exchange processes of H atoms, reaching a clear atomistic picture for the dynamic equilibrium of the reversible reactions and the Had migration.

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   ×

   @article{zheng2016dynamic,
     author = {Zheng, Qijing and Tan, Shijing and Feng, Hao and Cui, Xuefeng and Zhao, Jin and Wang, Bing},
     doi = {10.1021/acs.jpcc.6b02367},
     issn = {19327455},
     journal = {Journal of Physical Chemistry C},
     month = apr,
     number = {14},
     pages = {7728--7735},
     publisher = {American Chemical Society},
     title = {{Dynamic Equilibrium of Reversible Reactions and Migration of Hydrogen Atoms Mediated by Diffusive Methanol on Rutile TiO2(110)-(1×1) Surface}},
     corresponding_authors = {Wang Bing, Cui Xuefeng},
     first_authors = {Tan Shijing},
     url = {https://pubs.acs.org/doi/10.1021/acs.jpcc.6b02367},
     volume = {120},
     year = {2016}
   }
    

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3. Temperature- and Coverage-Dependent Kinetics of Photocatalytic Reaction of Methanol on TiO₂(110)-(1×1) Surface
   Feng, Hao^#; Tan, Shijing; Tang, Haoqi; Zheng, Qijing; Shi, Yongliang; Cui, Xuefeng*; Shao, Xiang; Zhao, Aidi; Zhao, Jin; Wang, Bing*
   Journal of Physical Chemistry C, 120, 5503–5514 (2016)
   Published: Feb, 2016
   Link bibtex abstract

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   We systematically investigated the photocatalytic reaction of methanol on the TiO2 (110)-(1 × 1) surface under irradiation with ultraviolet (UV) light performed at various conditions, using scanning tunneling microscopy (STM) jointed with temperature-programmed desorption (TPD) techniques. Our STM and TPD results show that the photocatalytic reaction is indeed initiated from the molecular methanol at the 5-fold coordinated Ti sites, as commonly ascribed to the methanol oxidation by the photogenerated holes, reflecting the highly photoactive nature of methanol. The formaldehyde yield from the TPD results is much smaller by a factor of 2/3 than the amount of dissociated methanol from the STM results at 80 K. This observation can be assigned to the reverse reaction during the TPD measurement, and may explain the lower yield of formaldehyde using molecular methanol than using methoxy. From the fractal-like reaction kinetics of methanol, we can associate the coverage-dependence of the spectral dimensions with the change for the diffusion of holes across the surface from a one-dimensional to a two-dimensional behavior because of the increased scattering species at higher coverages. Our results here provide a clear picture for the photocatalytic reaction of molecular methanol and may rationalize the different observations performed at various conditions.

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   @article{feng2016temperature,
     author = {Feng, Hao and Tan, Shijing and Tang, Haoqi and Zheng, Qijing and Shi, Yongliang and Cui, Xuefeng and Shao, Xiang and Zhao, Aidi and Zhao, Jin and Wang, Bing},
     doi = {10.1021/acs.jpcc.5b12010},
     file = {:home/zqj/work_dir/nsfc/ZhengQijing/2020_面上项目/参考文献/acs.jpcc.5b12010.pdf:pdf},
     issn = {19327455},
     journal = {Journal of Physical Chemistry C},
     number = {10},
     pages = {5503--5514},
     publisher = {American Chemical Society},
     corresponding_authors = {Wang Bing, Cui Xuefeng},
     month = feb,
     title = {{Temperature- and Coverage-Dependent Kinetics of Photocatalytic Reaction of Methanol on TiO2(110)-(1×1) Surface}},
     volume = {120},
     year = {2016}
   }
    

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2014

1. Nonnuclear Nearly Free Electron Conduction Channels Induced by Doping Charge in Nanotube-Molecular Sheet Composites
   Zhao, Jin^#; Zheng, Qijing; Petek, Hrvoje*; Yang, Jinlong*
   Journal of Physical Chemistry A, 118, 7255–7260 (2014)
   Published: Sep, 2014
   Link bibtex abstract

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   Nearly free electron (NFE) states with density maxima in nonnuclear (NN) voids may have remarkable electron transport properties ranging from suppressed electron-phonon interaction to Wigner crystallization. Such NFE states, however, usually exist near the vacuum level, which makes them unsuitable for transport. Through first principles calculations on nanocomposites consisting of carbon nanotube (CNT) arrays sandwiched between boron nitride (BN) sheets, we describe a stratagem for stabilizing the NN-NFE states to below the Fermi level. By doping the CNTs with negative charge, we establish Coulomb barriers at CNTs walls that, together with the insulating BN sheets, define the transverse potentials of one-dimensional (1D) transport channels, which support the NN-NFE states. (Graph Presented).

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   @article{zhaojin_jpca_2014,
     annote = {PMID: 24401149},
     author = {Zhao, Jin and Zheng, Qijing and Petek, Hrvoje and Yang, Jinlong},
     doi = {10.1021/jp410460m},
     issn = {15205215},
     journal = {Journal of Physical Chemistry A},
     corresponding_authors = {Petek Hrvoje, Yang Jinlong, Zhao Jin},
     month = sep,
     number = {35},
     pages = {7255--7260},
     title = {{Nonnuclear Nearly Free Electron Conduction Channels Induced by Doping Charge in Nanotube-Molecular Sheet Composites}},
     url = {http://dx.doi.org/10.1021/jp410460m http://pubs.acs.org/doi/abs/10.1021/jp410460m},
     volume = {118},
     year = {2014}
   }
    

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2010

1. Evidence for Competing Magnetic and Superconducting Phases in Superconducting Eu_1-xSr_xFe_2-yCo_yAs₂ Single Crystals
   He, Yu^#; Wu, Tao; Wu, Gang; Zheng, Qijing; Liu, Yuzhe; Chen, Hong; Ying, Jianju; Liu, Ronghua; Wang, Xiangfeng; Xie, Yali; Yan, Yajun; Dong, J. K.; Li, Shiyang; Chen, Xianhui*
   Journal of Physics Condensed Matter, 22, 235701 (2010)
   Published: May, 2010
   Link bibtex abstract

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   In single crystals of Eu1 - xSrxFe 2 - yCoyAs2, Co doping suppresses spin-density wave (SDW) ordering and induces a superconducting transition. A resistivity reentrance due to the antiferromagnetic ordering of Eu2 + spins is observed, indicating the competition between antiferromagnetism (AFM) and superconductivity (SC). It is striking that the resistivity reentrance can be completely suppressed by a small magnetic field due to a field-induced metamagnetic transition from AFM to ferromagnetism (FM). The resistivity reentrance can also be suppressed by the substitution of Eu2 + ions with nonmagnetic Ba2 +/Sr2 + to completely destroy the AFM ordering. These results indicate that the AFM order appears destructive to SC, while FM can coexist with the superconductivity. Further we find that magnon excitation exists in AFM ordering and can be suppressed by an applied field. Coexistence of SC from the FeAs layer and the inner field produced by the ferromagnetic Eu2 + layer suggest a possible p-wave component in the superconducting order parameter. \textcopyright 2010 IOP Publishing Ltd.

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   @article{he2010evidence,
     author = {He, Yu and Wu, Tao and Wu, Gang and Zheng, Qijing and Liu, Yuzhe and Chen, Hong and Ying, Jianju and Liu, Ronghua and Wang, Xiangfeng and Xie, Yali and Yan, Yajun and Dong, J. K. and Li, Shiyang and Chen, Xianhui},
     corresponding_authors = {Chen Xianhui},
     doi = {10.1088/0953-8984/22/23/235701},
     issn = {09538984},
     journal = {Journal of Physics Condensed Matter},
     number = {23},
     pages = {235701},
     publisher = {IOP Publishing},
     month = may,
     title = {{Evidence for Competing Magnetic and Superconducting Phases in Superconducting Eu1-xSrxFe2-yCoyAs2 Single Crystals}},
     volume = {22},
     year = {2010}
   }
    

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2. Electron Spin Resonance in EuFe_2-xCo_xAs₂ Single Crystals
   Ying, Jianjun^#; Wu, Tao; Zheng, Qijing; He, Yu; Wu, Gang; Li, Qiuju; Yan, Yajun; Xie, Yali; Liu, Ronghua; Wang, Xiangfeng; Chen, Xianhui*
   Physical Review B, 81, 52503 (2010)
   Published: Feb, 2010
   Link bibtex abstract

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   The temperature dependence of electron spin resonance (ESR) was studied in EuFe2-x Cox As2 system. The ESR spectrum of all the samples indicates that the linewidth strongly depends on the temperature. Moreover, the linewidth shows the Korringa behavior, indicating an exchange coupling between the conduction electrons and the Eu2+ ions. The linewidth, g factor and the integrate ESR intensity show anomalies at the temperature of the spin-density-wave (SDW) ordering. The linewidth below the SDW transition does not rely on the temperature. This gives the evidence for the gap opening at the TSDW. The slope of the linewidth is closely associated to TSDW and Tc. Such exotic behavior should be related to the nesting of the Fermi surface. \textcopyright 2010 The American Physical Society.

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   @article{ying2010electron,
     author = {Ying, Jianjun and Wu, Tao and Zheng, Qijing and He, Yu and Wu, Gang and Li, Qiuju and Yan, Yajun and Xie, Yali and Liu, Ronghua and Wang, Xiangfeng and Chen, Xianhui},
     doi = {10.1103/PhysRevB.81.052503},
     corresponding_authors = {Chen Xianhui},
     issn = {10980121},
     journal = {Physical Review B},
     number = {5},
     pages = {52503},
     publisher = {American Physical Society},
     month = feb,
     title = {{Electron Spin Resonance in EuFe2-xCoxAs2 Single Crystals}},
     volume = {81},
     year = {2010}
   }
    

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