Iron and nitrogen codoped carbon catalyst with excellent stability and methanol tolerance for oxygen reduction reaction

Abstract

A series of non-precious metal FexNC electrocatalysts for oxygen reduction reaction (ORR) were successfully synthesized using Fe(NO3)3, glucose, and melamine as the Fe, C, and N sources, respectively. The effects of the pyrolysis temperature and Fe/N contents on the catalytic performances are comprehensively investigated. Electrochemical results reveal that among the FexNC catalysts, Fe1.5NC-900-2 pyrolyzed at 900°C with the mass ratio of FeC to melamine being 1:10 proves the highest catalytic performance. The half-wave potential (E1/2) of ORR was 821 mV (vs reversible hydrogen electrode (RHE)) and only 36 mV lower than that on commercial Pt/C catalyst (857 mV). More importantly, Fe1.5NC-900-2 catalyst shows excellent stability and methanol tolerance. After 1000 sequential cycles, the E1/2 on Pt/C catalyst shifts negatively by approximately 60 mV, while for Fe1.5NC-900-2 catalyst, this shift is only 28 mV although the number of sequential cycles is increased to 8000. In the presence of methanol, the current decay in the chronoamperometric response at 1000 seconds is only 8% and also much lower than that on Pt/C catalyst (46%). The high catalytic performances arise from the abundant Fe3N active sites embedded in the carbon matrix of the FexNC catalysts. These findings can be used to discuss the catalytic mechanism of ORR on the FexNC catalysts and design the nonprecious metal carbon-based electrocatalysts for ORR.