Polydopamine bridging strategy enables pseudomorphic transformation of multi-component MOFs into ultrasmall NiSe/WSe2@NC heterojunctions for enhanced alkaline hydrogen evolution

Abstract

Heterojunction catalysts can synergistically promote the kinetics of energy-related reactions, but a significant challenge remains in fully exposing and engineering interfacial active sites. Herein, we developed a polydopamine (PDA) bridging strategy to construct multi-component metal-organic frameworks (MOFs) precursors to form ultrasmall NiSe/WSe2 @NC heterojunctions. Due to the ambiphilic binding of PDA to both NiMg-MOF and polyoxometalate (POM = H3PW12O40), subsequent selenization and MgO removal yield highly dispersed NiSe/WSe2 @NC with intimate heterointerfaces. By adjusting Mg2+ and POM loadings in PDA⊂NiMg-MOF-POM, the Ni:W:C ratios in NiSe/WSe2 @NC were fine-tuned, resulting in an optimized catalyst with low overpotential and high stability (21 mV at 10 mA·cm−2 for 60 h in 1.0 M KOH), rivaling the commercial 20% Pt/C (30 mV). X-ray absorption spectroscopy and density-functional theory calculations unveil that such “PDA bridging” strategy ensures highly exposed dual active centers and induced charge redistribution on heterointerface, resulting in accelerated water adsorption/dissociation and H2 evolution kinetics.