Symbiotic Ni3Se4/Ni heterostructure induced by unstable NiSe2 for enhanced hydrogen generation

Creating dual-site catalysts that can separately provide good OH and H interaction sites for water dissociation and hydrogen adsorption is proved to be an effective strategy for improving the activity of hydrogen generation in alkaline medium. However, there is still great challenge to construct a robust dual-site catalyst with multiple and efficient interfaces. Herein, taking thermodynamically unstable cubic NiSe2 phase as a self-sacrificial tem-plate, a symbiotic Ni3Se4/Ni heterostructure is successfully synthesized via in-situ electrochemical reduction of Ni3Se4/NiSe2 precatalyst. Density functional theory calculation suggests that the d-band center and electronic state of Ni sites are well optimized after forming the Ni3Se4/Ni heterostructure, which is favorable for the proper hydrogen adsorption. Benefiting from the good electrical conductivity, large electrochemical surface area, and distinct sites for water dissociation, Ni3Se4/Ni exhibits a low overpotential of 106 mV at-10 mA cm-2 for hydrogen generation in 1 M KOH.