Insight into the mechanism of 5-hydroxymethylfurfural electroreduction to 2,5-bis(hydroxymethyl)furan over Cu anchored N-doped carbon nanosheets

Design of non-noble metal electrocatalysts for biomass conversion to high-value chemicals and understanding the related catalytic mechanisms are of profound significance but have remained a major challenge. Here, we developed a novel biomass-derived electrocatalyst (denoted as Cu/NC), featuring with electron-deficient copper nanoparticles anchored on N-doped carbon nanosheets, for the electrochemical reduction of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF, a vital precursor of functional polymers). The optimized Cu/NC electrocatalyst exhibited an excellent performance with high Faradaic efficiency (89.5%) and selectivity (90.8%) of BHMF at a low concentration of HMF (18.1 mM). Even at a very high HMF concentration (108.6 mM), the Faraday efficiency and selectivity of BHMF could still reach 74.8% and 81.1%, respectively. This performance approached those of the reported noble metal-based electrocatalysts. Mechanism study revealed that the N doping in the Cu/NC catalyst could regulate the electronic structure of Cu, strengthening the adsorption of the HMF carbonyl group, and thus boosting the selectivity of BHMF. Additionally, strong electronic metal-support interactions of Cu and the N-doped carbon support optimized the charge transfer rate, thus promoting the dissociation of water to the active hydrogen (H*) species and boosting the reaction kinetic rate of H* and HMF.