The highly efficient electrocatalytic oxidation of 5-hydroxymethylfurfural on copper nanocrystalline/carbon hybrid catalysts: structure–function relations

2,5-Furandicarboxylic acid (FDCA) is a high-value platform molecule that can replace the fossil derivative terephthalic acid in the synthesis of important chemicals. FDCA can be synthesized from the oxidation of the biomass derivative 5-hydroxymethylfurfural (HMF). In this study, we loaded Cu-based catalysts with different morphologies and chemical states on carbon paper, and it was found that the Cu nanocrystalline/carbon paper catalyst with a thin and scattered dendrite structure (Cu(NSD)/CP) exhibits the best performance for the electrooxidation of HMF (96% yield and 100% selectivity for FDCA), which is attributed to the fact that the Cu0 and Cu1+ species in the catalyst are easily oxidized in situ to Cu2+ species, showing high catalytic activity during the reaction process. This paper highlights the importance of the identification of active sites and the rational design of catalysts based on structure–function relations.