Atomically-dispersed Fe-Nx and C–S–C ordered mesoporous carbons as efficient catalysts for the oxygen reduction reaction in a microbial fuel cell

Abstract

An efficient catalyst (Fe/S–N/C) possessing abundant ordered mesoporous was synthesized via a facile strategy, in which the active Fe-Nx and C–S–C species exhibited atomic dispersion. Attributing to its well-developed porosity, the total pore volume and specific surface area of Fe/S–N/C catalyst reach 0.556 cm3 g−1 and 980.9 m2 g−1 respectively. Electron microscopy results reveal the uniform dispersion of atomic Fe-Nx and C–S–C in this catalyst, which has inherited a polyhedral morphology derived from ZIF-8. X-ray spectroscopy measurements further validate that the Fe/S–N/C composite can provide abundant and highly efficient active sites for ORR. The atomic ratio of nitrogen is 4.28%, with high relative concentrations of the active pyridinic N and Fe-Nx. Furthermore, the Fe/S–N/C catalysts demonstrate significant ORR activity in the practical application of MFC devices. Based on a high open circuit potential (0.674 V) and maximum power density (1436.42 mW m−2) of the MFC device which uses the Fe/S–N/C as air-cathode catalyst, the Fe/S–N/C displays better catalytic activity than commercial 20% Pt/C catalyst. This investigation provides a new strategy to design an effective, low-cost ORR catalyst for MFC devices.