Engineering Ni_0.85Se/CoSe₂ 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 Ni_0.85Se/CoSe₂ heterojunction was constructed via electrodeposition, leveraging interfacial synergy to significantly enhance catalytic performance. Experimental results demonstrated that the heterojunction interface between N_i0.85Se and CoSe₂ 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 CoSe₂ facilitated the reconstruction of Ni_0.85Se, generating more active sites, lowering the kinetic barriers of UOR, and optimizing the adsorption of reaction intermediates on Ni sites. The Ni_0.85Se/CoSe₂ catalyst exhibited HER and UOR overpotentials of 102 mV and 1.292 V at 10 mA·cm^-2, respectively, with a urea-assisted electrolytic hydrogen production voltage of only 1.348 V at 10 mA·cm^-2. This study provides an innovative strategy for designing high-efficiency bifunctional electrocatalysts.