▎ 摘　　要

The rational design and precise synthesis of efficient and economical electrocatalysts are pivotal for the oxygen reduction reaction (ORR) process in energy related devices such as fuel cells and metal-air batteries. Herein, an in situ growth strategy is achieved to synthesize cobalt oxide hollow nanoparticles grown on nitrogen-doped reduced graphene oxide (Co3O4/N-rGO). Co3O4/N-rGO exhibits a half-wave potential of 0.75 V vs. RHE with favorable 4-electron transfer for the ORR in an alkaline environment. Characterization verifies the interaction between Co3O4 and the N-rGO support that promotes the catalytic reaction. Theoretical calculations further unravel that the (311) facet of Co3O4 possesses relatively high intrinsic catalytic activity compared with other low-index facets, contributing to the ORR performance of Co3O4/N-rGO. Accordingly, this Co3O4/N-rGO has been used as the cathode for zinc-air batteries, which reaches a relatively high power density and a specific capacity.