Modulating surface-state-induced band bending for efficient charge transport and photoelectrochemical hydrogen production over bismuth vanadate photoanode

The main challenge in photoelectrochemical (PEC) hydrogen production is designing efficient photoanodes. Although bismuth vanadate (BiVO₄) is an ideal photoanode light absorber. The fast charge recombination and poor charge transport rate of BiVO₄ seriously restrict its application as PEC water decomposition photoanode. In order to improve these effects, in this work, the surface composition of bismuth vanadate was manipulated by introducing trace amount of β-bismuth oxide onto the surface. After that, the optimized photoanode’s photocurrent and hydrogen production were significantly improved, which are mainly attributed to the improvement of depletion region width and band bending, photogenerated carrier transfer, and separation. This work clarifies that only trace amount of second phase is needed to improve the photoelectrochemical activity by constructing heterojunction. We expect that the proposed strategy is applicable to improve the photoelectron conversion in bismuth-based semiconductors.