Revealing Surface Charge Population on Flake-Like BiVO₄ Photocatalysts by Single Particle Imaging Spectroscopies

Visually observing the charge separation between different facets is of great importance for the development of high-efficiency photocatalysts. In this work, the techniques for visual observation and material strategy for catalyst synthesis were integrated to reveal the structure–activity relationship of a single BiVO4 photocatalyst. BiVO4 crystals with different ratios of (010)/(110) facets were synthesized by a pressure-assisted hydrothermal method. Spatially resolved surface photovoltage (SPV) indicated that photoinduced holes were prone to transfer from (010) facets to (110) facets on BiVO4. Both confocal fluorescence and Kelvin probe force microscopy (KPFM) evidenced the enhanced separation of photogenerated charge carriers by increasing the ratio of exposed (010) facets in flake-BiVO4. Profitting from the strategy of facet engineering, flake-BiVO4 presented remarkably increased activity for photocatalytic O2 production than that of truncated bipyramid-BiVO4. Our study provides a fundamental insight into the facet-dependent activity of BiVO4 single particle, which is beneficial for the rational design of faceted photocatalyst for environmental remediation and solar energy conversion.