Co3O4 nanorods with prevalent oxygen-vacancies confined by PDA-RGO nanosheets for excellent performances in supercapacitors

The rich oxygen-vacancies (O(V)s) on transition metal oxides are favorable for charge storage in supercapacitors, but are subjected to deactivation during charge-discharge cycles. Herein, we report that Co3O4@polydopaminereduced graphene oxide (Co3O4@PDA-RGO) nanocomposite could relieve the deactivation problem via the selfreviving of O(V)s. Besides the high specific surface area and ion/electron conductivities, Co3O4@PDA-RGO provides a robust framework to disperse Co3O4 nanorods, and the oxygen atoms in the vicinity of O(V)s account for 46.2% of oxygen-species. Especially, the resultant O(V)s can survive the rigorous charge-discharge cycles by virtue of the reversible redox with the aid of PDA-RGO. Given the advantageous structural characteristics, a high specific capacitance of 1562 F g(-1) (781C g(-1)) can be delivered at current densities of 0.5 A g(-1) and retain to 771 F g(-1) (385.5C g(-1)) at 20 A g(-1) by the Co3O4@PDA-RGO electrode. Moreover, 91% of its initial capacitance can be maintained after 10,000 consecutive charge-discharge cycles. The asymmetric supercapacitor, assembled by the Co3O4@PDA-RGO electrode and an activated carbon electrode, delivers a high energy density of 46.1 Wh kg(-1) at 800 W kg(-1). This study paves an efficient avenue to synthesize self-reviving O-V on metal oxides for the potential applications in supercapacitors.