Hard Lewis Acid Sites Modulate Competitive Adsorption in Nickel Oxide for Efficiency 5‐hydroxymethylfurfural Oxidation

Abstract The rational adsorption of reactant molecules is a fundamental requirement for efficient electrocatalysis. However, the strong adsorption of OH ⁻ on the anode surfaces hinders the efficient 5‐hydroxymethylfurfural electrooxidation reaction (HMFOR). Guided by the hard‐soft acid‐base (HSAB) principle, this work introduces hard Lewis acidic Mo sites into NiO (Mo _0.10 ‐NiO) to effectively modulate the adsorption configuration of OH ⁻ and HMF on the catalyst surface. In situ spectroscopy and theoretical calculations reveal that OH ⁻ is more readily adsorbed on hard acid Mo sites, while HMF adsorbs more strongly on the Ni sites. The optimized reactant adsorption configuration reduces the energy barrier of the rate‐determining step, thereby improving the catalytic efficiency of HMFOR. Benefiting from this strategy, Mo _0.10 ‐NiO exhibits a fourfold increase in catalytic activity compared to NiO, and achieves ampere‐level current density under high concentration of HMF. This study provides a feasible strategy for applying the HSAB principle to regulate reactant adsorption and achieve efficient biomass oxidation.