▎ 摘　　要

Development of effcient electrocatalysts for the oxygen reduction reaction (ORR) remains a key issue for the commercialization of metal-air batteries. In this study, the novel structured Co3O4 nanoparticles-modified alpha-MnO2 nanorods supported on reduced graphene oxide (Co3O4-MnO2/rGO) were synthesized with varying amounts of alpha-MnO2 via a facile two-step hydrothermal method. The relationship between the physical properties and the electrochemical results was investigated using X-ray diffraction spectrum, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammograms, electrochemical impedance spectroscopy and rotating disk electrode. The as-prepared Co3O4-MnO2 nanohybrid exhibits enhanced catalytic activity for ORR under alkaline condition compared with MnO2/rGO and Co3O4/rGO. Furthermore, it mainly favors a direct 4e-reaction pathway for ORR, which is attributed to the well-designed structure, the synergistic effect between Co3O4 and alpha-MnO2, and the covalent coupling between the Co3O4-MnO2 and reduced graphene oxide. The role of Co3O4 in Co3O4-MnO2 hybrid for catalyzing ORR also has been illustrated by varying the mass ratio of Co3O4 and MnO2, which reveals that the Co3O4-MnO2 with the ratio of 1: 1 has better catalytic activity.