Fe/Fe3C decorated 3-D porous nitrogen-doped graphene as a cathode material for rechargeable Li–O2 batteries

Abstract

Fe/Fe3C decorated 3-D porous N-doped graphene (F-PNG) is designed and synthesized via a one-step carbonization route. During the process, MIL-100(Fe), a kind of metal organic frameworks (MOFs) plays a structure-directing role. It is found that F-PNG with 3-D porous structure is constituted by N-doped graphene and extremely small Fe/Fe3C particles uniformly distribute on the surface of graphene. This rationally designed F-PNG possesses excellent oxygen reduction reaction and oxygen evolution reaction bifunctional electrocatalytic activity. While the material is explored as a cathode of Li–O2 batteries, it exhibits excellent electrochemical performances, delivering a discharge voltage platform of ∼2.91V and a charge voltage platform of ∼3.52V at 0.1mAcm−2, showing a good cycle performance and having a discharge capacity of ∼7150mAhg−1carbon+catalyst at 0.1mAcm−2. The excellent performance of the F-PNG electrode is attributed to the good catalytic activity of uniformly distributed extremely small Fe/Fe3C particles and N-doped graphene, the high electronic conductivity, and the 3-D porous structure. These results indicate that F-PNG can be an excellent cathode material for Li–O2 batteries, and MOFs-assisted synthesis method would be a promising new strategy for the synthesis of 3-D porous graphene materials.