▎ 摘　　要

Three-dimensional (3D) graphene has attracted considerable attention because of its unique physiochemical properties along with the merits afforded by porous materials. We report herein a scalable method to synthesize 3D hierarchically porous graphene from iron sheets based on a green electrochemical process. The hierarchically porous structure renders such 3D graphene suitable for a broad range of applications, as has been demonstrated by use as support for making efficient electrocatalysts toward the oxygen reduction reaction.