Effect of pH on the Reduction of Graphene Oxide on its Structure and Oxygen Reduction Capabilities in the Alkaline Media

Abstract

The reduction of many catalysts in aqueous media is usually carried out in a basic environment using most reducing agents. Graphene oxide (GO) was synthesized and reduced by sodium borohydride in an aqueous solution over a wide spectrum of pH values ranging from 1 to 13. X‐ray diffraction (XRD) and infrared spectroscopy (FTIR) confirmed the reduction of the graphene oxide at each respective pH value. Raman and X‐Ray photoelectron spectroscopy (XPS) spectra displayed an increased repair in the graphitic sp2 domain of the catalysts as the pH value of the solution was increased. Half‐cell electrochemical testing in basic media showed higher oxygen reduction capabilities in the catalysts that were reduced at higher pH values. The onset potential of the oxygen reduction reaction (ORR) also increased as the pH of the solution increased overall due to the increased repair in the graphitic domain of the catalysts reduced at higher pH values.