Pyridinic and pyrrolic nitrogen-rich ordered mesoporous carbon for efficient oxygen reduction in microbial fuel cells

Abstract

Non-noble cathode catalysts with high performance and low cost are vital for large-scale applications of microbial fuel cell (MFC) technology. In this study, pyridinic and pyrrolic nitrogen-rich ordered mesoporous carbon (PPN-OMC) synthesized by a facile strategy were successfully applied as cathode catalysts in MFCs. In MFCs with the currently used material, the maximum power density is 1420 ± 15 mW m⁻², which is comparable to a conventional platinum catalyst (Pt/C, 1425 ± 15 mW m⁻²), and the stability of the power output is even better. Mechanism exploration for efficient and stable power generation by electrochemical measurements revealed that the resulting PPN-OMC catalyst displayed superior electrocatalytic activity (nearly 100% of a four-electron oxygen reduction reaction (ORR) pathway) and durability (nearly no activity change after 100 000 potential cycles) for ORR in a neutral phosphate buffer solution (PBS). Further characterization of PPN-OMC implied that the existence of nitrogen substitution with high pyridinic and pyrrolic ratios of 39.8% and 35.1% and a large specific surface area of 1160 m² g⁻¹ benefitted the electrocatalytic activity and durability. MFCs with the PPN-OMC catalyst produced power much less expensively than those with Pt/C, indicating that the present PPN-OMC material might be used as an excellent alternative to Pt/C in MFCs.