Electrocatalytic activity of nitrogen-doped graphene synthesized via a one-pot hydrothermal process towards oxygen reduction reaction

Nitrogen-doped graphene (NG) materials have been prepared by hydrothermal reaction of graphite oxide (GO) with urea, and their electrocatalytic properties towards oxygen reduction reaction in 0.1 M KOH are investigated. The introduction of urea leads to successful nitrogen insertion in the form of pyridinic, pyrrolic, and graphitic bonding configurations with enhanced reduction of GO, and an increase in the mass ratio between urea and GO gives higher nitrogen contents, which is accompanied by more defects in microstructure. Reduction of O2 to OH− at lower overpotentials is favored by the incorporation of nitrogen, and the activity of NG is closely associated with nitrogen contents and microstructure. NG materials with ca. 7% nitrogen contents and moderate defect densities prepared from mass ratios of 1:200 and 1:300 (GO/urea) show the best performance.

► Nitrogen-doped graphene (NG) samples with different nitrogen contents are prepared. ► Nitrogen doping favors the reduction of oxygen to water at lower overpotentials. ► Properties of NG are closely related to nitrogen contents and microstructure. ► A nitrogen content of ca. 7% and moderate defect densities provide best activity.