Negative effects and mechanisms of phosphorus in electrolyte on the photoelectrochemical water splitting stability of BiVO4 photoanode

The industrial development of BiVO 4 photoanode–based photoelectrochemical (PEC) water splitting is constrained by the poor stability of the BiVO 4 photoanode. However, the effect of phosphorus (P) in commonly used electrolytes on BiVO 4 photoanode stability and the associated mechanism are still scarce. Herein, we investigate the effects of different P-containing electrolytes on the PEC performance of BiVO 4 , as well as the changes in the composition, microstructure, light-absorption properties, and carrier transport and separation efficiencies of BiVO 4 between before and after the reaction. Results demonstrate that at 1.23 V versus reversible hydrogen electrode (V RHE ), the photocurrent decay of BiVO 4 in all P-containing electrolytes after 24 h is >95 %. In acidic environments, H + and PO 4 3− convert BiVO 4 into BiPO 4 , with a larger band gap, resulting in decrease in PEC activity and stability. Under alkaline conditions, P deposits as a phosphorus oxide onto the BiVO 4 surface, resulting in severe carrier recombination and slower water oxidation kinetics. The 24-h photocurrent attenuation is alleviated to 33.5 % via a strategy involving low applied potential (0.8 V RHE ), introduction of labile V ions (NaVO 3 ), and deposition of a cocatalyst layer (NiOOH/FeOOH). This study emphasizes the effect of electrolyte composition on the PEC stability of BiVO 4 and provides a reference for the modification of BiVO 4 .