▎ 摘　　要

It is highly desirable but challenging to develop bifunctional catalysts for efficiently catalyzing both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in energy storage and conversion systems. Here a simple yet cost-effective strategy is developed to fabricate nitrogen and phosphorus dual-doped graphene/carbon nanosheets (N,P-GCNS) with N,P-doped carbon sandwiching few-layers-thick graphene. The as-prepared N,P-GCNS shows outstanding catalytic activity toward both ORR and OER with a potential gap of 0.71 V between the OER potential at a current density of 10 mA cm(-2) and the ORR potential at a current density of -3 mA cm(-2), illustrating that it is the best metal-free bifunctional electrocatalysts reported to date. The superb bifunctional catalytic performance is attributed to the synergistic effects between the doped N and P atoms, the full exposure of the active sites on the surface of the N,P-GCNS nanosheets, the high conductivity of the incorporated graphene, and the large surface area and hierarchical pores for sufficient contact and rapid transportation of the reactants.