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

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 BiVO 4 photoanodes involves the loss of V 5+ from the BiVO 4 lattice by dissolution. We demonstrate that the use of a V 5+ -saturated electrolyte, which inhibits the photooxidation-coupled dissolution of BiVO 4 , can serve as a simple yet effective method to suppress anodic photocorrosion of BiVO 4 . The V 5+ species in the solution can also incorporate into the FeOOH/NiOOH oxygen-evolution catalyst layer present on the BiVO 4 surface during water oxidation, further enhancing water-oxidation kinetics. The effect of the V 5+ species in the electrolyte on both the long-term photostability of BiVO 4 and the performance of the FeOOH/NiOOH oxygen-evolution catalyst layer is systematically elucidated. Photoelectrodes used to split water, driven by solar energy, often suffer from a lack of stability. Here the authors demonstrate that a V 5+ -saturated electrolyte can be used to inhibit photooxidation-coupled dissolution of a BiVO 4 photoanode, suppressing photocorrosion and allowing stable photocurrent generation over hundreds of hours.