NiCo‐Layered Double Hydroxide‐Decorated Oxygen Vacancy‐Engineered BiVO ₄ Photoanode for Efficient Photoelectrochemical Water Oxidation

Efficient charge separation and transfer are essential for high‐performance BiVO ₄ ‐based photoanodes in photoelectrochemical (PEC) water splitting. However, severe charge recombination and sluggish oxygen evolution reaction kinetics limit their practical application. In this study, a hydrogen‐treated BiVO ₄ (H‐BiVO ₄ ) photoanode decorated with NiCo‐layered double hydroxide (NiCo‐LDH) nanosheets is developed to significantly enhance PEC water oxidation through a synergistic defect‐engineering and a cocatalyst‐modification strategy. Hydrogen annealing introduces oxygen vacancies into the BiVO ₄ lattice, thereby increasing donor density and suppressing electron–hole recombination. The NiCo‐LDH cocatalyst promotes effective hole extraction and accelerates surface water oxidation. Accordingly, the optimized H‐BiVO ₄ /NiCo‐LDH photoanode exhibits a markedly reduced onset potential of 0.29 V versus the reversible hydrogen electrode (RHE) and delivers an enhanced photocurrent density of 1.87 mA cm ⁻² at 1.23 V versus RHE, which is approximately 3.8 times higher than that of pristine BiVO ₄ . Overall, this study demonstrates an effective strategy for improving the efficiency of BiVO ₄ ‐based photoanodes for solar‐driven water splitting.