Particle Size Influence on the Photocatalytic Water Oxidation Using Hydrothermal Synthesized BiVO 4

Bismuth vanadate (BiVO 4 ) is a promising photocatalyst for water oxidation owing to its visible‐light active bandgap and band structure. However, its performance is often hindered by inefficient charge separation and transport. Herein, a hydrothermal synthesis strategy that systematically engineers BiVO 4 particle size without altering facet composition is presented, enabling detailed analysis of size‐dependent photocatalytic activity. By controlling the reaction time prior to the heating stage, the particle size can be tuned while preserving a consistent (110)/(010) facet ratio. A pronounced enhancement in the apparent quantum yield (AQY) for water oxidation (using Ag + as a sacrificial reagent) was observed as particle size decreased, with a maximum AQY of 19.4% achieved by the sample with a mode particle size of 365 nm. This enhancement is attributed to increased active surface area and suppressed bulk recombination due to shortened carrier diffusion distance. These findings highlight particle size optimization as a key strategy for enhancing BiVO 4 photocatalytic efficiency.