Interface Engineering and Heteroatom Doping Trigger Multisite Synergism in V-Incorporated MoP/Cu3P to Accelerate Alkaline Hydrogen Evolution

Abstract

Efficient non-Pt electrocatalysts for the alkaline hydrogen evolution reaction (HER) are necessary for industrial water electrolysis. Cu-based materials are cheaper alternatives, but their performances are far from satisfactory due to slow water dissociation kinetics and weak Gibbs free energy of hydrogen adsorption (ΔG_H*). Herein, we propose to construct multiple sites with different activation functions in response to sluggish alkaline HER kinetics. A multi-interfacial, ultrasmall V-doped MoP and Cu₃P heterostructure (V-MoP/Cu₃P) was successfully fabricated by confined conversion of a V–Mo bimetallic polyoxometalate (POM) cluster embedded in a Cu-based metal–organic framework (MOF). The spatial separation of each POM cluster by the MOF and the inherent structure of each [VO₆] connecting four [MoO₆] octahedrons enable precise V incorporation in the MoP lattice and multi-interface coupling of the MoP and Cu₃P heterojunction. As a result, the interfacial charge redistribution occurs and the d-band centers are finely tuned, triggering a multisite synergism to encourage the adsorption and activation of H₂O, H–OH* bond breaking, and H₂ release. Consequently, V-MoP/Cu₃P exhibits significantly enhanced HER activity, even superior to the commercial 20% Pt/C catalyst at current densities exceeding 155 mA cm^–2, which indicates the feasibility of the V-MoP/Cu₃P catalyst as cheaper alternatives to Pt-based catalysts in industrial applications. This work provides new insight for the design of low-cost, high-abundance HER catalysts via multi-interface engineering and heteroatom doping to trigger multisite synergies.