Cation–Anion Synergistic Activation of Ni(OH) ₂ for Efficient Electrooxidation of 5‐Hydroxymethylfurfural

Coupling the oxidation of 5‐hydroxymethylfurfural (HMF) with the hydrogen evolution reaction can simultaneously reduce the energy barrier of HMF oxidation reaction and yield value‐added products. Nickel‐based catalysts demonstrate outstanding activity toward C─H bond activation, which is typically the rate‐determining step in the HMF oxidation reaction. However, their catalytic performance is often constrained by the sluggish formation of active sites and weak adsorption of organic reactants. In this study, we synthesized the Sr 0.1 Ni 0.9 (OH) 2 catalyst and investigated how carbonate ions in electrolytes promote the electrooxidation of HMF via proton‐coupled electron transfer (PCET). The comprehensive characterizations and density functional theory calculations collectively demonstrate that Sr incorporation effectively modulates the interfacial electronic structure and enhances carbonate adsorption, thereby facilitating PCET through a restructured interfacial hydrogen‐bond network that enhances proton relay efficiency. The Sr 0.1 Ni 0.9 (OH) 2 catalyst exhibits enhanced catalytic activity, delivering a Tafel slope of 29 mV dec −1 and a Faradaic efficiency of ∼90% for the production of 2,5‐furandicarboxylic acid. This work presents a cooperative catalyst–electrolyte strategy to modulate interfacial interactions, offering new avenues for ion‐regulated electrocatalysis in sustainable energy conversion applications.