Efficient electrocatalytic activity for oxygen reduction reaction by phosphorus-doped graphene using supercritical fluid processing

Oxygen reduction reaction (ORR) plays a vital role in various fields, such as combustion, corrosion and fuel cell applications. Herein, we report the production of phosphorus-doped reduced graphene oxide (P-RGO) using triphenyl phosphine as a phosphorus source and graphene oxide in supercritical fluid method. The ratio of phosphorus source and graphene oxide has been varied to obtain optimum P-doping. P-RGO materials are characterized through X-ray diffractometer, Raman, field emission scanning electron microscopy and X-ray photoelectron spectroscopy techniques. The electrocatalytic activity of P-RGO materials are studied using linear sweep voltammetry and their ORR performance are evaluated using linear sweep voltammetry-rotating ring disk electrode studies in 0.1 M KOH electrolyte. Among the three different P-RGO materials, RGO with phosphorus doping (2:1) delivered the best ORR performance (0.75 A mg−1) compared to commercial HiSPEC Pt/C (0.12 A mg−1) catalyst. The enhanced ORR activity could be ascribed to the existence of surface-active phosphorous sites over the RGO sheet surface.