▎ 摘　　要

The development of highly efficient catalysts for cathodes remains an important objective of fuel cell research. Here, we report Co3O4 nanoparticles assembled on a polypyrrole/graphene oxide electrocatalyst ((CoO4)-O-3/Ppy/GO) as an efficient catalyst for the oxygen reduction reaction (ORR) in alkaline media. The catalyst was prepared via the hydrothermal reaction of Coe. ions with Ppy-modified GO. The GO, Ppy/GO, and Co3O4/Ppy/GO were characterized using scanning electron microscopy, Fourier -transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The incorporation of Ppy into GO nanosheets resulted in the formation of a nitrogen -modified GO porous structure, which acted as an efficient electron-transport network for the ORR. With further anchoring of Co3O4 on Ppy/GO, the as-prepared Co3O4/Ppy/GO exhibited excellent ORR activity and followed a four-electron route mechanism for the ORR in alkaline solution. An onset potential of-0.10 V vs. a saturated calomel electrode and a diffusion limiting current density of 2.30 mA/cm(2) were achieved for the Co3O4/Ppy/GO catalyst heated at 800 degrees C; these values are comparable to those for noble -metal -based Pt/C catalysts. Our work demonstrates that Co3O4/Ppy/GO is highly active for the ORR. Notably, the Ppy coupling effects between Co3O4 and GO provide a new route for the preparation of efficient non -precious electrocatalysts with hierarchical porous structures for fuel cell applications. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.