Synergistically Accelerating Water Dissociation and Hydroxyl Spillover via Gradient Oxyphilic Structure on Mo‐SAs/Mo‐NiO for Efficient Alkaline Hydrogen Evolution

ABSTRACT Synergistically accelerating water dissociation and adsorption/desorption of intermediates is essential for designing high‐performance alkaline hydrogen evolution reaction (HER) electrocatalysts. Restricted by the Brønsted‐Evans‐Polanyi principle, strong *OH binding energy can accelerate water dissociation, yet it tends to cause *OH accumulation and active‐site poisoning. Herein, we rationally fabricate Mo single atoms supported on Mo‐doped NiO (Mo‐SAs/Mo‐NiO) to synchronously boost the alkaline HER elementary steps kinetics. NiO acts as an effective water‐dissociation promoter with a low energy barrier for splitting H 2 O into *H/*OH. Moreover, Mo doping and single‐atom sites jointly construct an atomic‐scale “energy downhill” pathway that drives spontaneous *OH transfer, enabling fast *OH removal and active‐site regeneration. Furthermore, Mo single atoms optimize the *H adsorption energy to expedite *H adsorption/desorption process. As a result, Mo‐SAs/Mo‐NiO delivers an ultralow overpotential of 23 mV at 10 mA cm −2 and a Tafel slope of 36 mV dec −1 in 1.0 m KOH, along with exceptional long‐term stability over 500 h with 16 µV h −1 attenuation. This work provides a universal design strategy for activating hydroxyl spillover to regulate the elementary steps of alkaline HER.