Copper-foam supported Ag microstructure for the electrochemical oxidative dehydrogenation of biomass-based furfural and 5-hydroxymethylfurfural

The electrochemical oxidative dehydrogenation of biomass-based furfural (FF) and 5-hydroxymethylfurfural (HMF) is an effective method for the simultaneous production of high-value-added products and H₂. Herein, a silver-loaded copper foam electrode is produced for the oxidative dehydrogenation of FF and HMF. The electrode is prepared through a galvanic replacement reaction between silver nitrate and a copper foam-supported copper microrod array. Our study shows that at low concentrations of silver nitrate, the copper microrods are transformed into a hollow structure composed of Ag particles and CuO nanosheets. As the concentration of silver nitrate increases, Ag dendrites gradually form on the electrode surface. In terms of catalytic activity, when the concentration of silver nitrate is 50 mM, the resulting electrode exhibits the highest current density. The electrolysis of 10 mM furfural and 10 mM HMF results in a furoic acid yield of 76% at 0.4 V_RHE and a 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) yield of ∼100% at 0.3 V_RHE, respectively. Even at 100 mM FF, the electrode can give a conversion of 94%, a furfural acid yield of 70%, and a faradaic efficiency of 90%. After three successive reaction cycles, the conversion rate of FF and the yield of furfural acid are not decreased, indicating good stability.