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

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 (ΔGH) 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.