Interconnected Fe, S, N-Codoped Hollow and Porous Carbon Nanorods as Efficient Electrocatalysts for the Oxygen Reduction Reaction

As promising precious metal-free oxygen reduction reaction (ORR) electrocatalysts, Fe–N–C catalysts still face a great challenge to meet the requirement of practical applications. In this study, Fe, S, N-codoped hollow and porous carbon nanorods (Fe–S–N HPCNRs) were designed with the aim of improving the performance of Fe–N–C catalysts from the perspective of composition and structure. They were successfully prepared using cysteine, Fe 2+ salt, and polydopamine-encapsulated ZnO nanorods (ZnO NRs@PDA) as precursors by a pyrolysis-acid etching strategy. The hollow and porous structure and composition of Fe, S, N, and C were verified by transmission electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, and X-ray photoelectron spectroscopy tests. At the optimum ratio of ZnO NRs@PDA/cysteine and pyrolysis temperature, the Fe–S–N HPCNRs display higher ORR activities than the control samples which are lack of one of the precursors. Electrochemical tests show that the ORR follows a 4e pathway with the Fe–S–N HPCNRs. In addition, the long-term stability and methanol tolerance of Fe–S–N HPCNRs are good and superior to those of 20 wt % Pt/C.