Fe/Co/C-N nanocatalysts for oxygen reduction reaction synthesized by directly pyrolyzing Fe/Co-doped polyaniline

Development of precious metal-free catalysts for oxygen reduction reaction (ORR) is of great significance for the practical application of fuel cells. In this article, we report the finding that the C-N composites containing Fe and/or Co (C-PANI, Fe/C-PANI, Co/C-PANI, and FeCo/C-PANI), produced by directly pyrolyzing the Fe- and/or Co-doped polyaniline (PANI) precursors, show efficient electroactivity for ORR both in acidic and in alkaline media. Among the prepared catalysts, Fe/C-PANI and Co/C-PANI present the most positive ORR onset potential that is 0.61 V (vs. SCE) in 0.5 mol L-1 H2SO4 solution or -0.1 V (vs. SCE) in 1 mol L-1 NaOH solution. In addition, the Fe/C-PANI catalyst shows the largest limiting-diffusion current density for ORR both in acidic and in alkaline media. A four-electron reaction of ORR on the Fe/C-PANI and Co/C-PANI catalysts is more dominant than a two-electron reaction. Fe/C-PANI catalyst also presents good electrocatalytic activity stability for ORR both in acidic and in alkaline media.