We revisit the polaron-mediated charge transport in BiVO4 photoanode. In addition to the improved charge transport and increased donor density, experimental and calculated results unravel that the electron small polaron hopping barrier near OVs of the BiVO4 is decreased by mild hydrogen doping, and the liberated polaron hopping is likely due to the filling of OVs with substitutional hydrogen dopants. This work illustrates an alternative understanding of the reasons for the commonly observed superior photoelectrochemical performances demonstrated in hydrogen-treated semiconductors.
