Electrochemical conversion of 5-hydroxymethylfurfural over CuNi bimetallic catalysts: the synergistic effect of interfacial active sites

Biomass upgrading by electrochemical means is of great scientific significance due to the environmentally friendly procedures and low energy consumption costs. Herein, electro-oxidation (ECO) of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) and electro-reduction (ECR) to 2,5-furandimethanol (BHMF) with high yield have been studied on CuNi-based bimetallic catalysts. Ni(OH)2-NCF and Cu-NCF achieved 99% and 96.5% yields at a HMF concentration of 10 mM in ECO and ECR, respectively. During ECO, the presence of Cu2O in the catalyst facilitated the adsorption of HMF, and the formed NiOOH in its vicinity promoted the proton coupled electron transfer process and thus resulted in the fast capture and removal of H protons. The presence of Cu-O-Ni linkages in the Ni(OH)2-NCF electrocatalyst was beneficial for the formation of Ni3+ active sites. During ECR, the synergistic effect between Cu and Ni species also contributed to the generation and spillover of Hads species and then enhanced the reactivity. ECO of HMF to FDCA and ECR to BHMF with high yield have been studied on CuNi-based bimetallic catalysts. The presence of the Cu-O-Ni interfacial area was beneficial for promoting the catalytic performance in ECO.