Mo-doping heterojunction: interfacial engineering in an efficient electrocatalyst for superior simulated seawater hydrogen evolution

Abstract

Exploring economical, efficient, and stable electrocatalysts for the seawater hydrogen evolution reaction (HER) is highly desirable but is challenging. In this study, a Mo cation doped Ni_0.85Se/MoSe₂ heterostructural electrocatalyst, Mo_x-Ni_0.85Se/MoSe₂, was successfully prepared by simultaneously doping Mo cations into the Ni_0.85Se lattice (Mo_x-Ni_0.85Se) and growing atomic MoSe₂ nanosheets epitaxially at the edge of the Mo_x-Ni_0.85Se. Such an Mo_x-Ni_0.85Se/MoSe₂ catalyst requires only 110 mV to drive current densities of 10 mA cm⁻² in alkaline simulated seawater, and shows almost no obvious degradation after 80 h at 20 mA cm⁻². The experimental results, combined with the density functional theory calculations, reveal that the Mo_x-Ni_0.85Se/MoSe₂ heterostructure will generate an interfacial electric field to facilitate the electron transfer, thus reducing the water dissociation barrier. Significantly, the heteroatomic Mo-doping in the Ni_0.85Se can regulate the local electronic configuration of the Mo_x-Ni_0.85Se/MoSe₂ heterostructure catalyst by altering the coordination environment and orbital hybridization, thereby weakening the bonding interaction between the Cl and Se/Mo. This synergistic effect for the Mo_x-Ni_0.85Se/MoSe₂ heterostructure will simultaneously enhance the catalytic activity and durability, without poisoning or corrosion of the chloride ions.