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.
