Bioinspired Co3O4/graphene layered composite films as self-supported electrodes for supercapacitors

A bioinspired Co3O4/graphene composite film was fabricated by an electrostatic self-assembly of polY(diallyldimethylammonium chloride)-stabilized porous Co3O4 flakes and graphene oxide nanosheets under vacuum filtration-induced directional flow in combination with subsequent thermal annealing. The resulting composite film was then empolyed as a self-supported electrode for supercapacitors. The narce-like layered architecture allows for an intimate interface contact and strong interactions between the two. This ensures a large ion-accessible surface and high structural integrality of the electrode during charging-discharging cycles. The high porosity of Co3O4 is capable of affording short diffusion paths of charges and high electrochemical utilization of the electrode. Graphene sheets also construct a highly conductive platform for fast charge transport and electrochemical reactions. Such unique bioinspired morphology and synergistic effects between porous Co3O4 flakes and graphene sheets promise excellent electrochemical performance. As expected, the free-standing electrode exhibits a specific capacitance of 623.8 F/g at a scan rate of 5 mV/s, and retains 83% of initial capacitance in the current density increasing from 1.0 to 8.0 A/g, suggesting large energy storage and high rate capabilities. The retention of initial capacitance remains 87% after 1000 cycles at 20 mV/s, indicating excellent cycling stability and reversibility. (C) 2017 Elsevier Ltd. All rights reserved.