Understanding Photocharging Effects on Bismuth Vanadate

Bismuth vanadate (BiVO 4 ) is a promising material for photoelectrochemical water oxidation. Recently, it has been shown that “photocharging” BiVO 4 results in an improved water oxidation performance. However, the understanding of how BiVO 4 is being improved has been lacking. Here we study the surface kinetics of BiVO 4 using intensity-modulated photocurrent spectroscopy and show that photocharging BiVO 4 results in both surface and bulk improvements. This result sheds light on how the surface charge transfer and bulk charge transport of BiVO 4 respond to illumination.