The Differentiation of Oxophilic Ce‐Induced Oxygen Vacancies and Single‐Atom Sites for Synergistically Boosting Alkaline Hydrogen Evolution

ABSTRACT Constructing active sites with distinct functions in catalysts is an effective strategy to boost the alkaline hydrogen evolution reaction (HER) involving multiple intermediates. However, the related intermediates exhibit a constrained proportional relationship, and competitive adsorption will inevitably occur among different sites. Here, this work reports a new‐style catalysis by introducing oxophilic Cerium (Ce) into the oxygen vacancies (Ov)‐rich nickel oxide support that is loaded with Ru single‐atom (Ru ₁ ‐Ce/NiO _1−x ). The as‐anticipated product exhibits an overpotential of only 37.5 mV at 10 mA cm ⁻² , along with an extremely high mass activity of 7450 mA mg ⁻¹ _Ru at an overpotential of 100 mV, and can operate stably for more than 50 h, significantly surpassing the catalyst without Ce (Ru ₁ ‐Ce/NiO _1−x ). Experimental and mechanistic studies demonstrate that the introduction of oxophilic Ce optimizes OH adsorption at oxygen vacancies (Ov), while the typical 4f orbitals of Ce regulate the electronic structure of Ru sites, thereby optimizing H adsorption and conversion at Ru sites. The distinctly differentiated Ov and single‐atom sites induced by Ce synergistically accelerate the alkaline HER kinetics. This work provides a novel insight into alleviating the competitive adsorption among different sites in the design of alkaline HER catalysts.