Electrochemical Oxidation of Glycerol to Dihydroxyacetone in Borate Buffer: Enhancing Activity and Selectivity by Borate–Polyol Coordination Chemistry

Selective electrochemical oxidation of glycerol, the major byproduct during the biodiesel production process, can not only make biodiesel production more environmentally benign and economically feasible but also generate value-added C3 chemicals that are important for medicinal and cosmetics applications. However, severe C–C bond breakage often occurs, which would lead to low C3 selectivity, especially on earth-abundant, low-cost transition metal electrocatalysts. In this study, by exploiting the coordination ability of borate ions with polyol molecules, we report enhanced and selective electrochemical oxidation of glycerol to ∼85% C3 chemicals (67% for dihydroxyacetone in detected liquid products, with an average production rate of 90 mmol m–2 h–1), using cobalt borate as the electrocatalyst in borate buffer electrolyte. The improved electrochemical activity and selectivity at different borate buffer concentrations and solution pH values have been explicitly correlated with the coordination ability of borate with glycerol under different circumstances, as revealed by 11B NMR spectroscopy studies. The strategy presented herein can be potentially extended to the selective upgrading of a broad scope of biomass-derived sugars and polyols, for producing value-added chemicals on low-cost non-noble metal electrocatalysts.