Role of Point Defects in Enhancing the Conductivity of BiVO4

ORAL

Abstract

Bismuth vanadate (BiVO4) is a promising photoanode for solar-to-fuel photocatalytic applications, and it has been extensively studied in recent years. However, the microscopic mechanism underlying the observed changes in electronic conductivity due to oxygen vacancies and nitrogen dopants remains unclear. Here, we combine electronic structure calculations at the hybrid density functional theory (DFT) level with constrained DFT, and we elucidate the role of defects in enhancing the transport properties of the material [1]. We show that at low temperature, oxygen vacancies give rise to deep levels within the fundamental gap of BiVO4; however even as deep levels, oxygen vacancies can act as effective n-dopants and polaronic charge carriers, due to their favorable position in energy relative to polarons in the pristine bulk. In addition, we show that N atoms can be easily introduced in n-doped BiVO4 and that the presence of substitutional nitrogen affects the formation energy of polarons, effectively contributing to an increase of the carrier mobility in the material. Our results reconcile apparently conflicting experiments and they may provide a foundation for polaronic defect engineering for photoanodes oxides. [1] H. Seo et al, Chem. Mater.
DOI: 10.1021/acs.chemmater.8b03201

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Presenters

  • Yuan Ping

    University of California, Santa Cruz, Department of Chemistry and Biochemistry, University of California Santa Cruz, Chemistry and Biochemistry, University of California, Santa Cruz

Authors

  • Hosung Seo

    Department of Physics and Department of Energy Systems Research, Ajou University, Physics and Energy Systems Research, Ajou University

  • Yuan Ping

    University of California, Santa Cruz, Department of Chemistry and Biochemistry, University of California Santa Cruz, Chemistry and Biochemistry, University of California, Santa Cruz

  • Giulia Galli

    Institute for Molecular Engineering, University of Chicago, Institute for Molecular Engineering and Materials Science Division, University of Chicago and Argonne National Laboratory, University of Chicago, Argonne National Lab, Institute for Molecular Engineering and Department of Chemistry, University of Chicago, University of Chicago and Argonne National Laboratory, The Institute for Molecular Engineering, University of Chicago, University of Chicago, Institute for Molecular Engineering, Univ. of Chicago; Department of Chemistry, Univ. of Chicago; Materials Science Division, Argonne National Laboratory