Nitrogen-doped Graphene as an Active Electrocatalyst for Oxygen Reduction Reaction

Abstract

Nitrogen-doped graphene (NG) sheets are synthesized by thermal reduction and ammonia treatment of graphene oxide (GO). Scanning electron microscopy has revealed a voile-like morphology of NG sheets, which highly contrasts from the stacked layers observed with GO. X-ray photoelectron spectroscopy has verified successful nitrogen-doping of NG sheets, and Raman spectroscopy has confirmed a higher degree of deformation in NG sheets due to the incorporation of heterogeneous nitrogen atoms. To evaluate NG sheets as a highly active oxygen reduction reaction (ORR) electrocatalyst, half-cell electrochemical testing has been employed using rotating disk electrode (RDE) in an alkaline aqueous electrolyte. NG sheets demonstrate a pseudo four-electron pathway O2 reduction, and a comparable ORR performance to that of a commercial carbon supported platinum (Pt/C) catalyst. This excellent ORR activity of NG sheets is most likely due to the active sites created by nitrogen-doping in the graphene sheets.