Amorphous Double Cocatalyst Enhanced BiVO₄ Photoanode for Efficient Solar-Driven Water Splitting

Photoelectrochemical (PEC) water splitting has emerged as an effective method to address energy and environmental challenges. In this study, a novel BiVO4/FeOOH/CACo photoanode is developed by integrating FeOOH and cobalt cinnamate (CACo) cocatalysts onto the BiVO4 surface for enhanced PEC water splitting. Compared with the reversible hydrogen electrode (RHE), the photocurrent density of the fabricated photoanode reached 3.15 mA cm-2 at 1.23 VRHE, which is 3.15 times greater than that of pure BiVO4, demonstrating good stability. Furthermore, the photoelectrochemical water splitting of hydrogen and oxygen production rates of the photoanode in a seawater environment achieved rates of 4.71 μmol h-1 cm-2 and 2.87 μmol h-1 cm-2, respectively. Systematic characterizations combined with density functional theory (DFT) calculations elucidate the dual cocatalyst synergy: FeOOH serves as a hole transport layer to accelerate carrier migration toward the CACo layer, while their cooperative interaction suppresses electron-hole recombination and enhances photogenerated carrier mobility. This dual cocatalyst system effectively suppresses the recombination of electron-hole pairs, enhances the migration of photogenerated carriers, and improves the photochemical water splitting activity. This study presents a feasible strategy for the application of amorphous cocatalysts in PEC systems.