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 -ɛd 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.
Keywords: alkaline volmer step; d‐band center; hydroxyl reductive desorption; interfacial water dissociation; work function.
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