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

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 NiSe/MoSe heterostructural electrocatalyst, Mo-NiSe/MoSe, was successfully prepared by simultaneously doping Mo cations into the NiSe lattice (Mo-NiSe) and growing atomic MoSe nanosheets epitaxially at the edge of the Mo-NiSe. Such an Mo-NiSe/MoSe catalyst requires only 110 mV to drive current densities of 10 mA cm in alkaline simulated seawater, and shows almost no obvious degradation after 80 h at 20 mA cm. The experimental results, combined with the density functional theory calculations, reveal that the Mo-NiSe/MoSe 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 NiSe can regulate the local electronic configuration of the Mo-NiSe/MoSe 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-NiSe/MoSe heterostructure will simultaneously enhance the catalytic activity and durability, without poisoning or corrosion of the chloride ions.