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 V_RHE, 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.