Pairing Electrocatalytic Reduction and Oxidation of Biomass-Derived 5-Hydroxymethylfurfural into Highly Value-Added Chemicals

Simultaneous electrocatalytic reduction and oxidation of 5-hydroxymethylfurfural (HMF) is crucial for biomass refineries. Herein, we report the unprecedentedly high efficiency of the nearly complete conversion of biomass-derived HMF to value-added products, achieving >95% selectivity at -0.4 V vs RHE by pairing electrocatalytic reduction and oxidation (PERO) reactions in a single electrochemical cell. At the cathode, we achieved 99% conversion of HMF to 2,5-dihydroxymethylfuran (DHMF) in ∼99% yield under mild conditions using a PtRu alloy. At the anode, we observed 99% conversion of HMF, nearly perfect selectivity for the oxidative product 2,5-furandicarboxylic acid (FDCA), and 100% Faradaic efficiency on a NiCo(OOH) _x nanosheets electrode. The kinetic isotope effect demonstrated that the rate-controlled step was a proton-independent electron transfer process, with minimal impact from substrate concentration variations. After assembling the synchronous reaction cell, the PERO of HMF generated high yields of DHMF (94%) and FDCA (86%), achieving a combined electron efficiency of 131%, nearly doubling the performance of uncoupled cells. This superior performance was attributed to the efficient generation of H* on the PtRu alloy for reduction, alongside the OH* active sites on the NiCo(OOH) _x nanosheets electrode for oxidation. This research provides a promising strategy for the sustainable electrocatalytic upgrading of biomass-derived chemicals.