Unravelling the Dynamic Modulation of Copper (Oxy)Hydroxides for Electrocatalytic Organic Nucleophile Oxidation

Electrocatalytic nucleophile oxidation (NOR) is pivotal for renewable energy and sustainable synthesis, yet the ambiguous nature of active sites hinders catalyst design. Herein, we thoroughly investigate the dynamic activation of CuO under NOR using surface voltammetry, in situ Raman, and impedance spectroscopies. Direct voltametric and spectroscopic evidences reveal that the adsorbed hydroxyl-bridged Cu^δ+-oxy species (μ₂-OH-Cu^δ+-oxy, 2 ≤ δ ≤ 3) are the catalytically active centers for the reaction. Experimental-theoretical synergy reveals that the dynamic μ₂-OH-Cu^δ+-oxy interacts with stabilized OH* to form a dual-site, dictating the structure-activity relationship. This mechanism enables near-quantitative conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid (97.1% yield/Faradaic efficiency) with > 100 h stability. The mechanistic insights we obtained show broad applicability across various nucleophilic substrates, where substituent effects, carbon chain flexibility, and α-hydrogen mobility govern reactivity variations. This study establishes dynamic active center engineering as a universal strategy for designing transition-metal (oxy)hydroxide catalysts, bridging electrocatalysis and precision organic synthesis.