Spectroscopic studies of heat-treated FeN_xC_y/C involved in electrochemical oxygen reduction under acid media

Carbon-incorporated FeN_x electrocatalysts (FeNC/C-T) have been synthesized by carbonizing a nitrogen-containing specie and iron precursor on carbon blacks at various heat-treated temperatures. The catalyst properties (crystalline structure, surface chemical states, oxidation state and co-ordination geometry) and their formation scheme of FeNC/C-T have been thoroughly examined by X-ray based spectroscopies such as X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The electrochemical performance of oxygen reduction reaction (ORR) and methanol tolerance were also investigated by rotating disk electrode tests in 0.5 M H₂SO₄. By combined results from XPS and XAS spectroscopies, the catalysts carbonized at 1073 K possess higher surface Fe/C and N/C atomic ratios with formation of carbons incorporated FeN₄ species were found to have the optimal electrocatalytic properties.