▎ 摘　　要

Nanoporous nitrogen doped carbon was used to modify the surfaces of graphene sheets by carbonizing a mixture of graphene oxide and phenol-melamine-formaldehyde (PMF) pre-polymer in the presence of a soft template (F127). The resulting graphene based composite sheets (G-PMFs) have a sandwich structure with one graphene layer and two nanoporous nitrogen-doped carbon layers. G-PMFs have large specific surface areas of 190 to 630 m(2) g(-1) and exhibited high electrocatalytic activity, good durability and high selectivity for the oxygen reduction reaction. The performance of the Zn-air fuel cell with a G-PMF anode was tested and found to be comparable to that of the Zn-air cell with a commercial Pt/C anode. Thus, these metal-free catalysts are promising for applications in practical fuel cells.