Electrocatalytic oxidation with water as the oxygen source provides a sustainable strategy for biomass transformation under mild conditions. The CuO nanorod-electrocatalyzed oxidation of furanics by water-derived oxygen was investigated. Two CuIII intermediates, (CuO2)− and (Cu2O6)6−, were detected on the surface of the working electrode in aqueous media. Interestingly, (Cu2O6)6‒, generated in the potential range of 1.35 to 1.39 V vs. RHE, induced the oxidation of furfuryl alcohol to furfural (≥ 98% yield), while (CuO2)−, generated at a potential greater than 1.39 V vs. RHE, led to the oxidation of furfuryl alcohol to 2-furoic acid (≥ 99% yield). The oxidation of 5-hydroxymethylfurfural (HMF) to furandicarboxylic acid catalyzed by CuO-nanorod proceeds via two different electrocatalytic pathways. In the first step for the oxidation of HMF, (Cu2O6)6− led to a pathway with preferential oxidation of the –CH2OH, while (CuO2)− induced the other pathway with preferential oxidation of the –CHO.
electrosynthesis;green chemical synthesis