Bifunctional MoNi4/Nickel Foam Electro‐Catalyst for Ultra‐Efficient Oxidation of High‐Concentration 5‐Hydroxymethylfurfural and HER

Abstract 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 4 alloy on nickel foam (NF) using a simple hydrothermal method followed by hydrogen reduction. Applied MoNi 4 /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 4 /NF is first oxidized to Ni 3+ species under the applied voltage, and after undergoing the electro‐catalytic HMFOR, then reduced to Ni 2−δ state (with a valence between 0 and +2) due to the electron‐donating effect from Mo. MoNi 4 /NF with more than one electron transfer between Ni 3+ and Ni 2−δ during the HMFOR enables it to have excellent electro‐catalytic oxidation ability toward HMFOR.