Well-dispersed FeN4 decorated mesoporous carbons for efficient oxygen reduction in acid media

Abstract

Synthesis of well-dispersed FeN4-doped mesoporous carbons (xFe-NMC) via a facile route is reported. These xFe-NMC samples invoke the carbonization of nitrogen-rich ionic liquids (strong coupling agents) and Fe precursors in mesoporous silicas. Characterizations of these xFe-NMC samples are conducted by a series of different spectroscopic and analytical techniques. The electrochemical performance of oxygen reduction reaction (ORR) and methanol tolerance are also studied by rotating disk electrode tests in 0.5 M H2SO4. Combined the results from X-ray diffraction, N2 adsorption-desorption isotherms, transmission electron microscopy and elemental analysis show that a high content of nitrogen (∼11.9 wt%) is successfully doped on ordered mesoporous carbons with high surface areas (∼1000 m2 g−1). Further investigations by X-ray photoelectron spectroscopy reveal that xFe-NMC samples with different ratios of pyridinic-N, Fe-N and pyrrolic-N are observed. Among the xFe-NMC samples, the 5.1Fe-NMC sample, which may be due to moderate specific surface area with high nitrogen doping on mesoporous carbons and more pyridinic-N species for the formation of the FeN4 active sites (verified by X-ray absorption spectroscopy), is found to have superior electrocatalytic activity for methanol-tolerant ORR in acidic media as compared to the typical commercial electrocatalyst (20 wt% Pt/C).