Elucidating the Role of Hypophosphite Treatment in Enhancing the Performance of BiVO4 Photoanode for Photoelectrochemical Water Oxidation

Slow water oxidation kinetics and poor charge transport restrict the development of efficient BiVO₄ photoanodes for photoelectrochemical (PEC) water splitting. Oxygen vacancy as an effective strategy can significantly enhance charge transport and improve conductivity in semiconductor photoanodes. Herein, we obtained BiVO₄ photoanodes with appropriate oxygen vacancy by treating them with hypophosphite, which significantly improved the PEC performance. The synthesized photoanode exhibits a remarkable photocurrent density of 3.37 mA/cm² at 1.23 V vs reversible hydrogen electrode with excellent stability. Interestingly, the performance improvement mainly originates from the oxygen vacancy rather than P doping. Our study provides insights in understanding the role of oxygen vacancy in PEC water splitting and strategies for designing more efficient photoelectrodes.