Microwave-assisted synthesis of mesoporous hemispherical graphite promoted with iron and nitrogen doping for reduction of oxygen.

Iron- and nitrogen-doped mesoporous hollow hemispherical graphite (NFe-HG) with average pore size of 12.3 nm, specific surface area of 1487 m2g-1 and 5.3% of N content is synthesized. The uneven carbon oxidation during microwave heating results in mesopores. The NFe-HG displays superior oxygen reduction reaction (ORR) activity with half wave potential (E 1/2) of 0.885 V in alkaline solution and comparable ORR activity (E 1/2 = 0.838 V) to commercial Pt/C in H 2 SO 4 solution. Due to the graphitization structure and trace residual iron, the NFe-HG performs high electrochemical stability. By comparing with spherical materials, the hemispherical structure of the NFe-HG shows the advantage of smaller volume with similar high specific surface. Image 1 • N doped hollow mesoporous hemispherical graphite with trace Fe is prepared. • Uneven microwave heating leads to mesopores in carbon. • The doping N contributes greatly to ORR performances. [ABSTRACT FROM AUTHOR]