Ru–Co Dual-Site Activation and NiO Hole Extraction for Efficient and Stable Photoelectrochemical Water Oxidation on BiVO4

Abstract

Photoelectrochemical (PEC) water splitting is a promising route for sustainable hydrogen production, yet the efficiency of the BiVO4 photoanode is limited by sluggish oxygen evolution kinetics and severe charge recombination. Herein, we report a Ru–Co dual-site activation and NiO hole extraction strategy for constructing a Ru0.49%-CoV-LDH/NiO/BiVO4 photoanode for efficient solar water oxidation. The incorporation of Ru into CoV-LDH generates electronically coupled Ru–Co dual active sites, while high-valent V induces electronic reconstruction within the layered double hydroxide framework to optimize the local coordination environment and interfacial charge transfer. Density functional theory calculations reveal that Ru acts as the dominant catalytic center and lowers the oxygen evolution reaction energy barrier. Meanwhile, the ultrathin NiO interlayer serves as a hole transport layer, enabling directional hole extraction from BiVO4 to the cocatalyst surface and suppressing interfacial charge recombination. Benefiting from the synergistic integration of dual-site activation and interfacial hole extraction, the optimized photoanode achieves a photocurrent density of 5.74 mA cm–2 at 1.23 V vs RHE, an applied bias photon-to-current efficiency of 1.69%, nearly unity charge separation efficiency, and excellent operational stability over 30 h. Furthermore, this strategy can be extended to Fe2O3 and WO3 photoanodes, demonstrating a general interfacial engineering approach for high-performance PEC water oxidation.