Green synthesis of ZnO-Co3O4 nanocomposite using facile foliar fuel and investigation of its electrochemical behaviour for supercapacitors

Currently, the sustainable fabrication of supercapacitors with enhanced properties is one of the significant research hotspots. Nevertheless, the performances of energy storage devices critically depend on their electrode materials. Accordingly, herein, we report the synthesis of a ZnO-Co3O4 nanocomposite using organic compounds of E. cognata, which was obtained via sol-gel synthesis. According to the synthesis strategy, the precursor solution was treated with a plant organic complex, and the consequent transformation to ZnO-Co3O4 was achieved via annealing a metal phyto-organic framework-derived complex in air. Furthermore, we tailored the surface chemistry of ZnO-Co3O4 using organic molecules of E. cognata. The present study successfully synthesized ZnO-Co3O4 nanocomposite with a particle size of 20 nm, which was subsequently investigated as an electrode material for supercapacitors. Consequently, it was revealed that the nano-features and phyto-organic functional groups provided abundant active sites for charge storage with a specific capacitance of 165 F g(-1), as calculated by the cyclic voltammetry. The phyto-functionalized nanocomposite exhibited an energy density of 4.1 W h kg(-1) and a power density of 7.5 kW kg(-1), which were calculated using charge discharge data. Therefore, all the findings effectively demonstrate the potential of the functionalized ZnO-Co3O4 nanocomposite as an effective electrode material for application as a supercapacitor on a practical scale.