Enhancing long-term photostability of BiVO4 photoanodes for solar water splitting by tuning electrolyte composition

Abstract

As the performance of photoelectrodes used for solar water splitting continues to improve, enhancing the long-term stability of the photoelectrodes becomes an increasingly crucial issue. In this study, we report that tuning the composition of the electrolyte can be used as a strategy to suppress photocorrosion during solar water splitting. Anodic photocorrosion of BiVO4 photoanodes involves the loss of V5+ from the BiVO4 lattice by dissolution. We demonstrate that the use of a V5+-saturated electrolyte, which inhibits the photooxidation-coupled dissolution of BiVO4, can serve as a simple yet effective method to suppress anodic photocorrosion of BiVO4. The V5+ species in the solution can also incorporate into the FeOOH/NiOOH oxygen-evolution catalyst layer present on the BiVO4 surface during water oxidation, further enhancing water-oxidation kinetics. The effect of the V5+ species in the electrolyte on both the long-term photostability of BiVO4 and the performance of the FeOOH/NiOOH oxygen-evolution catalyst layer is systematically elucidated.