Pyrolysis of iron phthalocyanine on activated carbon as highly efficient non-noble metal oxygen reduction catalyst in microbial fuel cells

Abstract

To improve the power generation of microbial fuel cells (MFCs), iron–nitrogen/activated carbon (Fe–N/AC), an excellent oxygen reduction reaction (ORR) electrocatalyst, was prepared by pyrolyzing iron(II) phthalocyanine (FePc)-coated AC, which was formed via an evaporation-induced self-assembly method. Given the high content of nitrogen and iron elements, crystalline structure, high surface area, and appropriate composition of micropores and mesopores, Fe–N/AC synthesized with 50.0 wt% of FePc loading on AC exhibits enhanced ORR electrocatalytic activity. The Fe–N/AC can catalyze ORR via an indirect four-electron pathway in neutral medium with onset potential of 0.883 V versus reversible hydrogen electrode and electron transfer number of 3.91. In comparison with AC, the charge transfer resistance and exchange current density of Fe–N/AC decreases by 62% and increases by a factor of three, respectively. The maximum power density of MFC using Fe–N/AC reaches 1092 mW m−2, which is 63.23% higher than that of AC and equal to that of Pt/C. This study proposes a new approach for the design of alternative non-precious metal ORR electrocatalysts in neutral pH medium, which may have potential application in practical MFCs as cathode catalysts in the future.