Mo₂N-Ni/NF Heterostructure Boosts Electrocatalytic Hydrogen Evolution with Pt-Like Activity

The sustainable development of a hydrogen economy requires hydrogen production from water electrolysis at a low cost, but the limited production of active and robust electrocatalysts using materials that are abundant on earth has restrained development. This article reports a heterostructure of a Mo₂N phase and metal Ni nanocrystals and its activities in the hydrogen evolution reaction (HER) in alkaline electrolytes. Hydrogen is produced by the catalyst in alkaline electrolytes at a density of 10 mA cm^-2 at an overpotential of only 20 mV with a small Tafel slope of 39.9 mV dec^-1, in which the catalyst exhibits a synergetic effect of compact Mo₂N and Ni interfacial connections, producing localized hotspots that accelerate water dissociation and hydrogen desorption. This makes the catalyst one of the most effective Pt-free species. Experimental and DFT theoretical results show that the exceptional HER electrocatalytic activity produced by the Mo₂N-Ni/NF heterogeneous structure is related to the unique highly unshielded structure and high intrinsic activity accompanied by a nearly thermoneutral H-adsorption energy.