Mo-doped NiFe-LDH drives efficient electrooxidation of biomass-derived furfurals to maleic acid

The renewable electricity-driven conversion of biomass-derived compounds into dicarboxylic acids represents an alternative to fossil-based processes, but achieving high selectivity and activity under mild conditions remains a significant challenge. Herein, we report Mo-doped NiFe-layered double hydroxide (NiFeMox-LDH) catalysts for electrosynthesis of maleic acid (MA) from selective electrooxidation of biomass-derived furfurals. Specifically, NiFeMo0.3-LDH with Mo content of 1.75 wt% affords MA in the highest yield of 93.2% to date, in KHCO3 electrolyte under the voltage range of 1.8–2.2 V (versus reversible hydrogen electrode). The Mo-doping in NiFeMox-LDH enhances activity of lattice oxygen and alters adsorption modes of 5-hydroxymethylfurfural (HMF) and intermediate, thus steering the products from furandicarboxylic acid obtained over NiFe-LDH to MA. Additionally, succinic acid can be produced in 99.5% selectivity via MA electroreduction on a copper foam cathode paired with HMF electrooxidation over NiFeMo0.3-LDH. Membrane electrode assembly electrolyzer delivers a Faradaic efficiency of 65.2% for MA production from HMF electrooxidation with a production rate of 252 mmol g−1 h−1 and a partial current density of 326 mA cm−2.