▎ 摘　　要

Co3O4 nanoplate/graphene sheet composites were prepared through a two-step synthetic method. The composite material as prepared was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The platelet-like morphology of Co3O4 leads to a layer-by-layer-assembled structure of the composites and a good dispersion of Co3O4 nanoplates on the surface of graphene sheets. The electrochemical characteristics indicate that the specific capacitance of the composites is 337.8 F g(-1) in comparison with the specific capacitance of 204.4 F g(-1) without graphene sheets. Meanwhile, the composites have an excellent rate capability and cycle performance. The results show that the unique microstructure of the composites enhances the electrochemical capacitive performance of Co3O4 nanoplates due to the three-dimensional network of graphene sheets for electron transport increasing electric conductivity of the electrode and providing unobstructed pathways for ionic transport during the electrochemical reaction.