▎ 摘　　要

A cost-efficient and environmentally benign strategy for large-scale production of metal oxide/metal-decorated 3D porous graphene directly converted from waste papers with a cobalt(II) complex was successfully developed. The resulting Co3O4/Co immobilized in porous graphene served as a spacer to prevent restacking of graphene and also provided more accessible active sites. As a demonstration, the oxygen reduction reaction (ORR) was chosen to show the catalytic activity of the high-added-value Co3O4/Co@graphene composite. Due to the synergistic catalytic effects between Co3O4 and graphene combined with a hierarchical porous structure, the synthesized 3D functional porous graphene can function as an efficient ORR catalyst with comparable performance to that of a Pt/C catalyst, which shows its potential application in fuel cells.