Polyhedral Coordination Determined Co-O Activity for Electrochemical Oxidation of Biomass Alcohols

Earth-abundant transition metal oxides are promising electrocatalysts for oxidation of biomass alcohols. Here, CoO and Co3O4 are selected as representative cobalt oxide catalysts and grown on carbon fiber paper (CFP) electrodes to reveal the interplay between electronic structure and catalytic activity of catalysts for oxidation of glycerol, diols, and monohydric alcohols. In situ electrochemical tests elucidate that the CoO/CFP electrode has lower interfacial impedance, higher charge transfer, faster oxidation rate, and thereby the higher catalytic activity for alcohol oxidation than the Co3O4/CFP electrode. Especially for glycerol oxidation, the CoO/CFP electrode only requires 1.32 V to reach 10 mA cm(-2), the potential is 120 mV lower than that for the Co3O4/CFP electrode. The CoO/CFP electrode can also produce value-added products such as formate, acetate, and glycolate with high selectivity and efficiency at low energy consumptions from oxidation of biomass alcohols. Theoretical calculations further confirm the dominant role of octahedrally coordinated Co-O sites in adsorption, activation, and oxidation of C3-C1 alcohols. This work sheds light on the design of highly efficient transition metal oxide catalysts for oxidation of alcohols by populating octahedral sites in the crystal structure.