In Situ Development of a 3D Cu-CeO2 Catalyst Selective in the Electrocatalytic Hydrogenation of Biomass Furanic Compounds

The renewable electricity-driven electrocatalytic hydrogenation of biomass-derived furanic compounds produces biopolymer (polyurethane) precursors under mild reaction conditions. The widely used Ag and Cu electrocatalysts failed in the selective conversion of the aldehyde into the alcohol in concentrated electrolytes due to the contribution of the electrodimerization. Herein, we proposed 3D CeO2-based catalysts for the electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) electrolytes (0.02, 0.05, and 0.10 M) to 2,5-bishydroxymethylfuran (BHMF). An electrodeposition approach was adopted to coat CeO2 on Cu open-cell foams. The ex-situ characterization of electrocatalysts revealed that they were made of a CeO2 layer containing Cu species. The migration of Cu from the foam to the coating started during the electrodeposition, while the electroreduction conditions provoked the formation of Cu particles. The in situ characterization by X-ray absorption spectroscopy evidenced that the Ce4+ to Ce3+ reduction occurred just after the application of the cathodic potential; moreover, copper species were reduced to Cu0 during the experiments. The combination of partially reduced CeO2 and Cu particles not only provided selective reaction sites but also increased the electrical conductivity of the electrode. Consequently, the in situ-developed Cu-CeO2 electrocatalysts promoted the selective electrocatalytic hydrogenation of the more concentrated 0.10 M HMF electrolytes, overperforming previously reported AgCu materials at -0.51 V vs RHE.