Bifunctional MoNi/Nickel Foam Electro-Catalyst for Ultra-Efficient Oxidation of High-Concentration 5-Hydroxymethylfurfural and HER

The electro-catalytic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) provides an attractive route to produce 2, 5-furandicarboxylic acid (FDCA) as a substitute for terephthalic acid used in the plastics industry. Herein, we prepared MoNi alloy on nickel foam (NF) using a simple hydrothermal method followed by hydrogen reduction. Applied MoNi/NF as the bifunctional electrodes for the electro-catalytic HMF oxidation reaction (HMFOR) and HER, 98.7 % FDCA yield and 97.3 % Faraday efficiency (FE) can be achieved even with HMF concentration as high as 200 mM. Notably, no obvious deactivation was observed after ten consecutive cycles. In-situ Raman, XANES and EXAFS results show that the nickel species of MoNi/NF is first oxidized to Ni species under the applied voltage, and after undergoing the electro-catalytic HMFOR, then reduced to Ni state (with a valence between 0 and +2) due to the electron-donating effect from Mo. MoNi/NF with more than one electron transfer between Ni and Ni during the HMFOR enables it to have excellent electro-catalytic oxidation ability toward HMFOR.