Enhanced Electro-Oxidation of Ethylene Glycol over Cu/C Catalysts Using Different Forms of Carbon

Abstract

In present work copper has been studied as the active material supported on different forms of carbons, such as activated carbon (AC), reduced graphene oxide (RGO), alumina based templated carbon (TC) and vulcan carbon (VC), for electro-oxidation of ethylene glycol (EG). Different carbon supports were observed to impart different physical and electrochemical characteristics to the catalysts in spite of presence of same active metal with similar loadings of 20 wt%. 20Cu-RGO showed highest current density of 5.61 mA/cm2 followed by 20Cu-VC at 2.59 mA/cm2 in acidic medium. The higher electrochemical surface area, pore size, metal dispersion, work function and content of oxygen containing functional groups were observed to favour better performance for electro-oxidation. The time constants for all the catalysts decreased in acidic medium and increased in basic medium upon addition of ethylene glycol. It was observed that electrochemical reaction was slower process in comparison to charge transfer irrespective of the type of medium. Oxalic acid was obtained as the main product during electro-oxidation of EG in both medium. The glyoxylic acid was detected as intermediate only in basic medium. The catalysts proved to be physically and chemically stable in both mediums.