Dual-Driven Interfaces of a CoP/CoO Cocatalyst on a Host Photocatalyst for Rapid Charge Transport in Solar-Driven H2 Evolution

Abstract

The construction of efficient and nonprecious cocatalysts, along with the establishment of rapid interfacial charge migration pathways to host semiconductors, is a major process in enhancing photocatalytic water splitting performance and remains a formidable challenge. Herein, the composition of CoP/CoO cocatalysts on g-C₃N₄ is regulated through phosphating for efficient and stable H₂ evolution. Comprehensive analyses reveal that the CoO nanocrystals, possessing a bandgap of 1.95 eV, are uniformly loaded onto g-C₃N₄ with a portion undergoing an in situ transformation to metallic CoP, thereby forming a well-defined interfacial energy level structure for carrier separation. Moreover, the CoP/CoO cocatalysts exhibited a lower hydrogen adsorption Gibbs free energy (ΔG_H) than that of the mono CoP or CoO. The optimal CoP/CoO/g-C₃N₄ exhibits an attractive and stable rate of solar-driven H₂ evolution at 0.86 mmol·g^–1·h^–1, surpassing the rates of CoO/g-C₃N₄ and Pt/g-C₃N₄ by 30 and 1.5 times, respectively. The dual-driven interfaces of CoP/CoO/g-C₃N₄ provide a 2-fold acceleration for directional carrier transfer, in conjunction with accelerated surface reaction kinetics, resulting in efficient and stable H₂ evolution. This scalable strategy, focusing interfacial engineering for rapid carrier transfer, offers a novel perspective in the design of highly active cocatalysts to boost the photocatalytic application.