Insights into the mechanism of the enhanced visible-light photocatalytic activity of black phosphorus/BiVO4 heterostructure: a first-principles study

Abstract

Bismuth vanadate (BiVO₄)-based photocatalysts as a typical solar-water-splitting material have attracted much interest due to their moderate band gap, fine hole conductivity and good stability. In this work, we perform a comprehensive first-principles study of the structural, electronic and optical properties of a black phosphorus BP/BiVO₄ heterostructure, which was realized with remarkable performance in pure water splitting in a very recent experiment. Firstly, the optoelectronic properties and charge transport between BP and BiVO₄ are systematically elucidated. We find that the positions of the valence/conduction band edge of BP and BiVO₄ change with the Fermi level and form a type-II heterostructure with a high optical absorption coefficient. Furthermore, the charge density difference and Bader charge analysis indicated that the internal electric field will facilitate the separation of e⁻/h⁺ pairs at the BP/BiVO₄ interface and restrain the carrier recombination. Therefore, the present work provides insightful understanding of the physical mechanism and superior photocatalytic performance of this new synthesized system and offers instructions for fabricating superior BiVO₄-based heterostructure photocatalysts.