▎ 摘　　要

Hierarchically porous carbon sheets decorated with transition metal carbides nano particles and metal-nitrogen coordinative sites have been proposed as the promising non precious metal oxygen electrocatalysts. In this work, we demonstrate a facile and low-cost strategy to in situ form Fe/N codoped hierarchically porous graphene-like carbon nano sheets abundant in Fe-N-x sites and Fe3C nanoparticles (Fe-N/C) from pyrolyzing chestnut shell precursor. The as-prepared Fe-N/C samples with abundant Fe-N-x sites and Fe3C nanoparticles show superior electrocatalytic activity to oxygen reduction reaction (ORR) in the alkaline medium as well as high stability and methanol tolerance due to the integration of multi-factors: the high content of Fe-N-x active sites, the coexistence of Fe3C, the unique hierarchically porous structure and high conductivity of carbon matrix. The optimal Fe-N/C-2-900 sample exhibits a more positive half-wave potential (-0.122 V vs. Ag/AgCl (3 M) reference electrode) than commercial 20 wt% Pt/C catalyst. This study provides a facile approach to synthesize Fe3C nanoparticles decorated Fe/N co-doped hierarchically porous carbon materials for effective oxygen electrocatalyst. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.