Highly selective and efficient electrocatalytic synthesis of glycolic acid in coupling with hydrogen evolution
Si Di, Bingyan Xiong, Lisong Chen, Jianlin Shi
Abstract
Armed with both hydroxyl and carboxyl groups, glycolic acid is an especially high-value-added chemical applied in diverse areas. However, its large-scale production suffers heavily from harsh synthetic conditions and poor selectivity. Here, an electrocatalytic approach has been developed for glycolic-acid production by electro-oxidation of ethylene glycol in alkaline solution on a PdAg electrocatalyst in situ grown on nickel foam (PdAg/NF). Resultantly, as low as 0.57 V versus reversible hydrogen electrode at 10 mA cm−2 is needed for ethylene glycol electro-oxidation, which is markedly (980 mV) lower than that of oxygen evolution in the same electrolyte without ethylene glycol. Moreover, glycolic acid can be electro-catalytically produced most efficiently at an extremely high current density of 300 mA cm−2 without the occurrence of oxygen evolution. When coupled with a Pt cathodic catalyst, a cell potential of 1.02 V is necessary for cathodic hydrogen production at faradic efficiency of 100%.