Direct observation of anisotropic small-hole polarons in an orthorhombic structure of BiVO4 films

作     者：A. Chaudhuri L. Mandal X. Chi M. Yang M. C. Scott M. Motapothula X. J. Yu P. Yang Y. Shao-Horn T. Venkatesan A. T. S. Wee A. Rusydi 

作者机构：NUSSNI-NanoCore National University of Singapore Singapore 117576 Singapore Singapore Synchrotron Light Source National University of Singapore 5 Research Link Singapore 117603 Singapore Department of Physics National University of Singapore Singapore 117542 Singapore Institute of Materials Research and Engineering A*STAR 2 Fusionopolis Way Singapore 138634 Singapore Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore Singapore 117546 Singapore Department of Materials Science and Engineering University of California Berkeley California 94720 USA Electrochemical Energy Laboratory Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) 28 Medical Drive Singapore 117456 Singapore Department of Materials Science and Engineering National University of Singapore Singapore 117583 Singapore 

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

年 卷 期：2018年第97卷第19期

页      面：195150-195150页

核心收录：

基　　金：National Research Foundation Singapore, NRF, (MOE2015-T2-2-065, NRF-CRP 8-2011-06, R-144-000-346-112) National Research Foundation Singapore, NRF 

主　　题：Polarons X-ray absorption spectroscopy X-ray diffraction X-ray photoelectron spectroscopy 

摘      要：Here, we report an anisotropic small-hole polaron in an orthorhombic structure of BiVO4 films grown by pulsed-laser deposition on yttrium-doped zirconium oxide substrate. The polaronic state and electronic structure of BiVO4 films are revealed using a combination of polarization-dependent x-ray absorption spectroscopy at VL3,2 edges, spectroscopic ellipsometry, x-ray photoemission spectroscopies, and high-resolution x-ray diffraction with the support of first-principles calculations. We find that in the orthorhombic phase, which is slightly different from the conventional pucherite structure, the unoccupied V 3d orbitals and charge inhomogeneities lead to an anisotropic small-hole polaron state. Our result shows the importance of the interplay of charge and lattice for the formation of a hole polaronic state, which has a significant impact in the electrical conductivity of BiVO4, hence its potential use as a photoanode for water splitting.