Surface etching to tune the behaviours of photogenerated charges on a decahedron BiVO4 crystal for efficient photocatalysis†

Abstract

Achieving spatial charge separation between different facets on a single crystal is one of the most efficient approaches to improve the charge separation efficiency of semiconductor-based photocatalysts. However, how the exposed facets affect spatial charge separation is still elusive, and the control of the behaviors of photogenerated charges remains challenging. In this work, decahedron BiVO₄ was chosen as a model photocatalyst, and a surface etching strategy using sodium hydroxide solution was employed, resulting in selective etching of the {010} facets while the {110} facets remained intact. The distribution of photogenerated electrons was found to be gradually transferred from the etched {010} facets to the {110} facets, which was accompanied by the reverse transfer of photogenerated holes. This result indicates that the distribution of photogenerated electrons and holes on different facets can be precisely modulated by tuning the surface properties of exposed facets. This modulation, enabled by the surface etching treatment herein, could give rise to much improved photocatalytic performance of decahedron BiVO₄ for the degradation of various aromatic and heteroaromatic environmental pollutants. This work provides a feasible strategy to modulate the charge behaviors of semiconductors, which will be instructive in constructing efficient photocatalysts for solar energy conversion.