In situ fabrication of a rose-shaped Co2P2O7/C nanohybrid via a coordination polymer template for supercapacitor application

Herein, we report the construction of a rose-shaped cobalt phenylphosphonate coordination polymer [Co(PhPO3)]viathe solvothermal method, which has been used as a precursor to prepare porous Co2P2O7/C nanohybrid through a thermal transformation process in N-2. By controlling the calcination temperature, a series of polyporous rose-shaped Co2P2O7/C-X(X= 600, 700, 800, 900 and 1000) have been successfully obtained. The prepared Co2P2O7/C-Xmaterials presentin situ hybrid nanostructures and a unique polyporous structure, which will provide rich electrochemical active centers and enough migration paths for electrons and electrolyte for fast and deep faradaic reactions. As a supercapacitor electrode, the optimized Co2P2O7/C-900 demonstrated a specific capacitance of 349.6 F g(-1)at 1 A g(-1)and remarkable cycling performances (97.33% retention after 3000 cycles at 2 A g(-1)). Moreover, using the porous rose-shaped Co2P2O7/C-900 as a cathode with 3D porous graphene gel (3DPG) as an anode, an asymmetric supercapacitor Co2P2O7/C-900//3DPG was fabricated. The device showed an energy density of 21.9 W h kg(-1)at a power density of 0.375 kW kg(-1)and outstanding cycle stability of maintaining 106.25% initial capacity after 10 000 cycles at 3 A g(-1).