▎ 摘　　要

The transition metal and nitrogen co-doped graphene as efficient electrocatalysts of oxygen reduction reaction (ORR) is promising to achieve large-scale applications of the full cells. In this work, we investigated the active sites and ORR mechanism on IrN4 doped divacancy graphene (IrN4-Gra) by using the density functional method. The active sites are identified as the IrN4 moiety and its adjacent ten C atoms. ORR on IrN4-Gra is a four-electron process. OOH hydrogenated into OH + OH is the kinetically most favorable pathway. The rate-determining step is OOH + H -> OH + OH with energy barrier 1.01 eV. The predicted working potential is 0.41 V. Hence, IrN4-Gra might be a promising ORR catalyst. (C) 2018 Elsevier Inc. All rights reserved.