Interlayer Ag nanoparticle-anchored Mo,W:BVO/NiCo2O4 heterojunctions for the synergistic enhancement of photoelectrochemical water splitting activity†

Spinel oxide NiCo₂O₄ is introduced as an emerging material for photocatalytic oxygen precipitating catalysts. The NiCo₂O₄ hollow spheres prepared using the template method combine a large specific surface area with high electrical conductivity and exhibit excellent catalytic properties. Building on this significant improvement, our research aims to enhance the photoelectrochemical performance of Mo,W:BVO/NiCo₂O₄ heterojunctions by integrating hollow NiCo₂O₄ during BiVO₄ fabrication, thereby improving the charge transfer and water oxidation kinetics of Mo,W:BVO/NiCo₂O₄ photoanodes. Additionally, the deposition of Ag as a middle layer prevents oxidation issues during the PEC process, resulting in the most significant enhancement of photocurrent. Compared to a reversible hydrogen electrode, the obtained photoanodes achieve a photocurrent density of 5.30 mA cm⁻² at 1.23 V vs. RHE. Through experimental and theoretical demonstrations, our work provides novel insights into modifying BiVO₄ photoanodes using oxygen precipitating catalysts and noble metals to improve their photoelectrochemical performance.