BiVO4 photoanode modified with p-type BiOBr and NiOOH as hole transfer layers for improved photoelectrocatalysis

BiVO₄ stands out as a prime photoanode material for photoelectrocatalytic applications. Nevertheless, a critical challenge of BiVO₄ lies in its inefficient charge separation and kinetically limited oxygen evolution. To overcome the downsides of BiVO₄, a p-n heterojunction photoanode has been engineered through the electrodeposition of p-type BiOBr onto BiVO₄, followed by NiOOH co-catalyst modification. The integration of BiOBr and NiOOH with BiVO₄ boosts its photocurrent density to 0.96 mA/cm²(1.23 V vs. RHE), a 300 % enhancement relative to pure BiVO₄. Remarkably, the BiOBr/BiVO₄/NiOOH photoanode outperforms BiVO₄ for a 280 mV reduction of the onset potential and a 57 % reduction in charge transfer resistance. Furthermore, the IPCE at 350 nm increases dramatically from 11.6 % (BiVO₄) to 33.0 %, reflecting a 2.8-fold enhancement in light utilization. The significantly enhanced photoelectrocatalytic performance of the BiOBr/BiVO₄/NiOOH photoanode stems from the dual mechanism by the p-n heterojunction and the oxygen evolution co-catalyst, which establishes a unidirectional hole transport pathway from BiVO₄ through BiOBr to NiOOH, substantially reducing charge recombination losses and accelerating the oxygen evolution reactions. This study establishes a foundation for advancing composite photoanodes derived from BiVO₄.