Electrochemical oxidation of glycerol to value-added products have attracted interest over the years, particularly owing to its possibility of coupling with hydrogen production, which could be the key to achieve a sustainable clean energy source. Herein, an earth-abundant metal oxide-based catalyst, cuprous oxide (Cu2O) has been demonstrated as an efficient and stable electrocatalyst for glycerol oxidation under mild basic condition (pH 9). A high selectivity of three-carbon products of ca. 90%, namely dihydroxyacetone (DHA), glyceraldehyde (GLYD) and glyceric acid (GLAC), was obtained at a high current density over 5.5 mA cm-2 without the occurrence of oxygen evolution. More importantly, DHA, which is one of the most important value-added products was attained with selectivity as high as 45%. Moreover, the effects of electrolyte temperature on the catalytic performance for glycerol oxidation were further studied. It is found that by increasing reaction temperature to 50 °C, glycerol oxidation reaction over Cu2O was initiated at dramatically lower onset potentials while glyceric acid turned out to be the primary products. Reaction pathway and mechanistic study of glycerol oxidation was investigated via electrochemical studies paired with high-performance liquid chromatography, where it was found that at higher reaction temperature, DHA and GLYD would be isomerized to each other, and further converted to GLAC spontaneously. The result of this work showed the potential to utilize an inexpensive metal oxide-based catalyst in valorization of glycerol to high-value three-carbon products.

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