Customizing interfacial hydroxyl coverage on MnCoOxHy with electric field confinement for selective 5-hydroxymethylfurfural electrooxidation in dilute electrolyte

State-of-the-art 5-hydroxymethylfurfural electrooxidation typically requires a highly alkaline anolyte (e.g., 1 M KOH) to efficiently produce 2,5-furanedicarboxylic acid (FDCA). Scaling up of this technique is limited by excessive acid/base consumption and substantial organics degradation. These challenges can be mitigated by employing dilute electrolytes, provided that sufficient interfacial OH− availability is maintained. Here, we present tip-enhanced electric field confinement to promote OH− adsorption under mildly alkaline conditions (0.1 M KOH), thereby enhancing the activity of the electrocatalytic 5-hydroxymethylfurfural oxidation reaction (e-HMFOR). Morphology-tunable Mn-doped cobalt oxyhydroxide electrodes, MnCoOxHy-NNS (nanoneedles) and MnCoOxHy-NWS (nanowires), exhibit distinct and enhanced selectivity. Remarkably, the high-curvature tips of MnCoOxHy-NNS generate an enhanced electric field that enriches interfacial OH− coverage. This feature expedites formyl group oxidation and strengthens the electrode’s electrophilicity, steering the oxidation pathway from 2-formyl-5-furanediformic acid (FFCA, 78.1% yield) to FDCA, 95.3% yield. Additionally, Mn doping in MnCoOxHy-NNS stabilizes the CoOOH phase and promotes OH* accumulation, enhancing e-HMFOR while suppressing competing water oxidation. Techno-economic analysis interprets that the improved e-HMFOR economy in 0.1 M KOH reduces the cost for feedstocks by ~ 67.9%. This work establishes a reliable strategy for customized electrocatalyst design in biomass oxidation under low alkalinity, eliminating the need for high-concentration electrolytes.