Boosting graphene electrocatalytic efficiency in oxygen reduction reaction by mechanochemically induced low-temperature nitrogen doping

Abstract

Mechanochemically induced low-temperature preparation of nitrogen-doped few-layer graphenes (N-Gr) and their application as electrocatalysts of oxygen reduction reaction (ORR) in alkaline medium was shown. The proposed approach allowed achieving a high proportion of graphitic nitrogen atoms. Such doping of N-Gr caused healing of vacancies in its structure, and also lead to the increased charge carrier density and high reduction ability that support advanced electrocatalytic characteristics in ORR (the onset and half-wave potentials equal to 0.98 and 0.77 V vs RHE, the average electron transfer number close to four, the Tafel slope about 60 mV/dec), the absolute values of which are close to those of the platinum-based catalyst. A model of N-Gr-based zinc-oxygen cell could provide a discharge current density of ∼40 mA/cm2 at a potential of 1 V and peak power density about 100 mW/cm2, as well as high cathode stability during cycling.