Unraveling the Potential‐Regulated Selectivity of the Cu‐Based Catalyst in 5‐Hydroxymethylfurfural Electro‐Oxidation

2,5-Furandicarboxylic acid (FDCA), prepared via the 5-hydroxymethylfurfural electro-oxidation reaction (HMFOR), is a promising bio-based plastic monomer for biodegradable polymer production. However, the sluggish hydroxyl oxidation kinetics inhibit the HMFOR efficiency. In this study, CuOxHy is grown on Cu foam as a model electrocatalyst to investigate the active phases of the Cu-based catalyst in the HMFOR, elucidate their oxidation mechanisms and adsorption behaviors at varying potentials, and ultimately to reveal the potential-regulated selectivity of the Cu-based catalyst. Experimental and theoretical studies reveal that CuIII─OOH, generated from CuO at high potentials, exhibits enhanced catalytic activity, enabling HMFOR to proceed via an indirect oxidation process that favors aldehyde oxidation. A further increase in potential activates the direct oxidation process of CuIII─OOH, selectively oxidizing hydroxyl groups owing to the increased substrate coverage on the catalyst, which hinders aldehyde adsorption. This study offers a new strategy for enhancing the selectivity towards the oxidation of specific functional groups in value-added biomass conversion processes.