Competitive Optimization of Interfacial Water Dissociation and Hydroxyl Reductive Desorption of MoCoNi‐Based Catalysts for Superior Alkaline Hydrogen Evolution

Abstract Nano‐heterointerface serves as a catalytic center for water dissociation promoted by the concerted interaction of *OH on oxide and *H on nitride. Kinetic energetics of water dissociation and hydroxyl (de)stabilization are vital to surface coverage of reactive *H and surface charge for *OH reductive desorption. electron paramagnetic resonance spectra of DMPO‐H and DMPO‐OH unravel radical nature of water‐dissociated *H and *OH. coherent synergism of interfacial ensemble and electronic effects realizes TOF/η−ɛ _d volcano as the net result of work‐function‐directed competition between interfacial water dissociation (covalent control) and *OH reductive desorption (ionic control) kinetics, manifesting that alkaline HER volcano shaped by d‐band descriptor originates from intricate balance guided by work function descriptor. Orchestrated with alkali metal cations on fine‐tuning covalent/ionic interaction between catalyst surface and water‐derived intermediates, microrod‐array N–MoCoNiAl/NF electrode (NF═Ni foam) drives 10 mA cm ⁻² at overpotential of 10 mV in 1 m KOH. The proposed pathway may provide insight into how the peculiar electronic structure of multi‐site heterojunction and the interfacial hard‐soft covalent/electrostatic interactions impact molecular‐level mechanism for efficient Volmer kinetics.