Ultra-high-performance doped carbon catalyst derived from o-phenylenediamine and the probable roles of Fe and melamine

•Doped carbon catalyst Fe/oPD–Mela was prepared by pyrolyzing a hybrid precursor.•The catalyst shows graphene-like structure with high surface area up to 384 m2 g−1.•The catalyst exhibits superior ORR activity to commercial Pt/C in alkaline medium.•The high performance of the catalyst may be caused by its high active N content.•ORR reaction changed from the 2e− process to the 4e− process by adding melamine.

By pyrolyzing hybrid precursor of poly o-phenylenediamine (oPD), melamine and iron in an Ar atmosphere, a doped carbon catalyst, Fe/oPD–Mela, with high surface area, high pyridinic and graphitic nitrogen content, is prepared successfully. This catalyst exhibit high performance towards the oxygen reduction in both alkaline and acid mediums; actually its activity surpassed that of commercial Pt/C catalyst in an alkaline medium. In 0.1 M KOH, the half-wave potential is high up to 0.91 V, which is about 50 mV higher than that of Pt/C, and the current density at 0.90 V is about 2.4 times to that of the Pt/C catalyst. And in an acid medium, its activity approaches that of a Pt/C catalyst. Furthermore, this catalyst also showed high stability and impressive immunity towards methanol. The probable roles of added iron and melamine are investigated intensively; both of them are playing an important role in the ORR activity of Fe/oPD–Mela.

Graphical abstractThe oPD and melamine are copolymerization and a hybrid copolymers is formed (a). Excessive melamine and melamine monomer in the hybrid copolymers will pyrolyzing and which will lead to forming fluffy, a irregular graphene-like material Fe/oPD–Mela (b). The nitrogen content of nitrogen in Fe/oPD–Mela is high up to 6.83 at%. And it exhibits high oxygen reduction activity in both alkaline and acid mediums. In 0.1 M KOH, its current density is about 2.4 times to that of the Pt/C catalyst at 0.90 V.Figure optionsDownload full-size imageDownload as PowerPoint slide