Electrochemical reduction of HMF to synthesize added value compounds using CuAg electrodes

In biorefining, Green electrochemistry offers an intelligent approach to produce valuable chemicals that are not derived from fossil fuels. In this study, we demonstrate the electrochemical reduction of 5-hydroxymethylfurfural (HMF), a biomass-derived compound, into 2,5-bis-hydroxymethylfuran (BHMF), which serves as a fundamental component in the polymer industry. This reaction was performed using Cu and Ag electrodes, but a better performance was obtained by combining the properties of the two metals in Ag decorated Cu foils. Additionally, by means of Impedance Spectroscopy IS we could uncover that the incorporation of Ag onto Cu electrodes not only increases the active area of the electrodes but also improves both the HMF adsorption on Cu and the catalytic properties of Ag. This synergistic effect leads to a more efficient reduction of HMF. Nonetheless, the diffusion of reactive species imposes a constraint on the increase in current. Finally, the observed inverted hysteresis in the cyclic voltammetry is attributed to variations in the amount of HMF adsorbed on the electrode surface during the forward and reverse directions of the cyclic voltammetry. Unlike other systems such as solar cells, where this effect is linked to the presence of a low frequency inductive behavior which, in this case, plays a negligible role.