Dopant‐Directed Activity in NiOOH: Distinct Fe, Co, and Cu Roles in Electrocatalytic HMF Oxidation to FDCA

Electrocatalytic oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA) offers a sustainable route to bio‐based plastics that can replace petroleum‐derived PET. Here, we systematically compare NiOOH and Fe−, Co−, and Cu‐doped NiOOH electrocatalysts synthesized by pulsed electrodeposition with matched loadings and dopant distributions, enabling a direct one‐to‐one assessment of dopant effects on HMFOR in alkaline media. Among all catalysts, NiFeOOH delivers the highest activity and selectivity across the full potential range, reaching an FE FDCA of 87.42% and an FE HMFOR of 98.85% at 1.53 V versus reversible hydrogen electrode. Scaling the electrode area fivefold achieves near‐quantitative HMF conversion (99.98%) with a 95.45% FDCA yield over 6 h while maintaining excellent durability. Mechanistic investigation via potential‐dependent product analysis, in situ Raman spectroscopy, spontaneous kinetics, and density functional theory reveals dopant‐specific functions: Fe strongly tunes the Ni 3+ electronic structure to weaken Ni 3+ –O bonding, enhance substrate adsorption, and accelerate charge transfer; Co primarily increases electrochemical surface area, boosting site density but not intrinsic site reactivity; and Cu alters the rate‐determining step, redirecting the reaction pathway. These insights show that different dopants offer distinct design levers in Ni‐based HMF oxidation reaction (HMFOR) catalysts and motivate multidopant strategies to jointly tune electronic structure, morphology, and reaction pathways for improved performance.