▎ 摘　　要

Graphene is a very attractive 2D carbon material, while the synthesis route of functional graphene is complex and complicated. The purpose of this study is to develop Co/N co-doped grapheme catalyst for ORR.Herein, a facile and universal pyrolysis method to explore the preparation of Co-N co-doped graphene through thermal exfoliation of 3D Co0.5Zn0.5-ZIF metal-organic framework by dimension reduction, and study the specific changes during process of dimensionality reduction, aiming at contributing to the transformation mode of 3D materials into 2D materials. The results showed that LiCl and KCl play different roles, namely the building carbon layer, pore-creating and exfoliation and acted simultaneously when they are added. A unique ultrathin 2D morphology of Co/N co-doped graphene, pores formed with the volatilization of zinc ions, and the appearance of abundant Co-N, active sites, which endow efficient catalytic activity of oxygen reduction reaction (ORR) in the alkaline electrolyte. Co/N-Go-Li/K-800 possesses the superior ORR activity among Co/N-Go-Li/K-T with an onset potential (0.15 V vs Ag/AgCl) and higher limiting current density(J@ -0.8 V vs Ag/AgCl) (-5.20 mA.cm(-2)) closer to Pt/C (0.17 V vs Ag/AgCl and -5.86 mA.cm(-2)). (C) 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.