Balancing Competitive Intermediate Behaviors on D‐f Hybridized Ni‐MOF‐Derived Catalysts for Alkaline Hydrogen Oxidation Reaction

ABSTRACT Although Ni‐based catalysts have been regarded as promising Pt‐free catalysts for alkaline hydrogen oxidation reaction (HOR), the competitive adsorption of H species and O‐containing species on Ni active sites significantly hinders its practical application. Metal‐organic frameworks (MOF) have emerged as highly favorable precursors for electrocatalyst synthesis due to their large specific surface area and abundant accessible active sites. Herein, a Ni‐SmO _x /C catalyst is constructed by the incorporation of f‐block rare earth element (Sm) into Ni‐based MOF derivative, demonstrating its remarkable alkaline HOR behaviors on account of the well‐balanced competitive behaviors of diverse reaction intermediates on abundant active sites, induced by the interfacial charge redistribution and microenvironment modulation. Combining experimental and theoretical analyses, it can be concluded that the built‐in electric field and d‐f orbital coupling between Ni and SmO _x in Ni‐SmO _x /C can optimize electronic structure and induce interfacial charge redistribution, which in turn fine‐tunes and well‐balances the reaction intermediate behaviors. More critically, it can be inferred that oxophilic SmO _x species serve as additional active sites for OH species with enhanced binding strength and create a local OH‐enriched microenvironment, thereby mitigating the competitive adsorption behaviors on Ni sites and ensuring an efficient supply of diverse reactive species for HOR.