Niobium Doping in BiVO₄: Interplay Between Effective Mass, Stability, and Pressure

Abstract

Abstract We have applied density functional theory to study the electronic structure changes caused by Nb incorporation in BiVO 4 and the application of external pressure. The overall solubility of Nb in BiVO 4 is usually high, and the presence of oxygen vacancies affect the dopability of Nb in BiVO 4 . Through the analyses of the chemical‐potential landscape, we have determined the single‐phase stability zone of BiVO 4 with the Nb doping. The most favorable Nb doping is simultaneous substitutions at both V‐ and Bi‐sites. Even though Nb substitution at only V‐site is next favorable, the band gap change is not very significant which agrees with an earlier experiment. However, it does change the electron effective mass by 20 % owing to the presence of Nb 4d bands in the conduction bands, which explains better catalytic activity by Nb‐doped BiVO 4 . In addition, application of external pressure the single‐phase stability zone in the chemical‐potential landscape. We have also focused on the local structural distortions near the Nb doping site, especially on the BiO 8 octahedra. We have shown here that pressure‐induced symmetrization of BiO 8 dodecahedron lowers the electron's effective mass further and therefore can help to improve the photoconduction property of BiVO 4 .