Highly efficient electrooxidation of 5-hydroxymethylfurfural (HMF) by Cu regulated Co carbonate hydroxides boosting hydrogen evolution reaction

The biomass electrochemical oxidation has attracted worldwide attention owning to its carbon-neutral and sustainable nature. Here, different morphologies of CoCu-carbonate hydroxides (CH) electrodes are prepared through one-step hydrothermal method for 5-hydroxymethylfurfural electrocatalytic oxidation (HMF-ECO) to high-valued 2,5-furandicarboxylic acid (FDCA) for the first time. The results illustrate that Cu can regulate CoCu–CH morphologies from 1D nanorods to 2D ultra-thin nanosheets besides modulating the catalytic compositions . The optimal Co 1 Cu 1 –CH exhibits hybrid nanostructures containing the 1D nanorods and 2D ultra-thin nanosheets , which has the largest ECSA and specific surface area, as well as the smallest Tafel slope and impedance. The oxidation potential of HMF-ECO is 1.42 V vs RHE with the conversion of HMF 99.57%, the selectivity for FDCA 99.91%, and the FE 98.88%. In addition, Cu can promote the conversion of Co 2+ to the favorable Co 3+ for HMF-ECO on the catalyst surface . Density functional theory calculation indicates that Cu can improve charges transfer to HMF and lower its adsorption energy . In situ Raman spectra tests indicate that cobalt species is the active site for HMF-ECO. Furthermore, at 1.42 V vs RHE, the coupling of HMF-ECO and hydrogen evolution reaction shows that the cathodic hydrogen evolution rate is 92.33 L h −1  m −2 , which is 3.69 times more than water splitting. This work provides a special structures material to process intensification of HMF electrooxidation coupling hydrogen production .