Understanding Photocharging Effects on Bismuth Vanadate.

Bismuth vanadate (BiVO4) is a promising material for photoelectrochemical water oxidation. Recently, it has been shown that "photocharging" BiVO4 results in an improved water oxidation performance. However, the understanding of how BiVO4 is being improved has been lacking. Here we study the surface kinetics of BiVO4 using intensity-modulated photocurrent spectroscopy and show that photocharging BiVO4 results in both surface and bulk improvements. This result sheds light on how the surface charge transfer and bulk charge transport of BiVO4 respond to illumination.