Photogenerated carrier dynamics at the anatase/rutile TiO2 interface

作     者：Yanan Wang Yongliang Shi Chuanyu Zhao Qijing Zheng Jin Zhao 

作者机构：Department of Physics Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei Anhui 230026 China International Center for Quantum Design of Functional Materials CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics University of Science and Technology of China Hefei Anhui 230026 China 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2019年第99卷第16期

页      面：165309-165309页

核心收录：

基　　金：Anhui Initiative in Quantum Information Technologies, (11704363) Department of Energy Office of Biological and Environmental Research National Key Foundation of China National Natural Science Foundation of China, NSFC, (11620101003) National Natural Science Foundation of China, NSFC Department of Science and Technology, Government of Kerala, (2016YFA0200604, 2017YFA0204904) Department of Science and Technology, Government of Kerala Fundamental Research Funds for the Central Universities, (WK3510000005) Fundamental Research Funds for the Central Universities 

主　　题：First-principles calculations Lifetimes & widths Wide band gap systems Molecular dynamics 

摘      要：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.