Engineering NiSe/CoSe heterojunction for enhanced bifunctional Catalysis in Urea-Assisted hydrogen production.

Coupling the hydrogen evolution reaction (HER) with the urea oxidation reaction (UOR) represents a highly promising energy-saving strategy for hydrogen production. However, the development of cost-effective and high-performance bifunctional electrocatalysts remains a challenge. In this study, a NiSe/CoSe heterojunction was constructed via electrodeposition, leveraging interfacial synergy to significantly enhance catalytic performance. Experimental results demonstrated that the heterojunction interface between NSe and CoSe greatly improved charge transfer efficiency, optimized the adsorption free energy of H* during HER, and accelerated water dissociation. In situ characterizations and theoretical calculations further revealed that the formation of CoSe facilitated the reconstruction of NiSe, generating more active sites, lowering the kinetic barriers of UOR, and optimizing the adsorption of reaction intermediates on Ni sites. The NiSe/CoSe catalyst exhibited HER and UOR overpotentials of 102 mV and 1.292 V at 10 mA·cm, respectively, with a urea-assisted electrolytic hydrogen production voltage of only 1.348 V at 10 mA·cm. This study provides an innovative strategy for designing high-efficiency bifunctional electrocatalysts.