A novel method for production of core-shell nanoparticles and its energy storage application

Researchers are interested in the production of metal oxide-carbon core-shell nanostructures due to their superior performance, stability as well as optical and electrical properties. However, their synthesis approaches are quite lengthy and also excessive chemicals use hampered performance adversely. This study proposed a novel method for producing core-shell NPs (GO@ZnO), i.e. ZnO nanostructures wrapped in graphene oxide (GO). The Core-shell NPs are produced using electrochemical (EC) and electrical discharge (ED) hybrid processes. A two-step approach is used, in which at first ZnO colloidal solution is prepared using zinc electrode as the core, and then the graphite electrode produces the shell. For zinc and graphite electrodes, experimental settings include 2 M electrolyte concentration, 120 V voltage, 10% and 20% duty cycles. The core-shell structures are confirmed through TEM images. The best electrochemical activity of core-shell (GO@ZnO at NaOH medium) was observed, with a high specific capacitance of 1042 F/g at 2 A/g current density. At 5000 cycles, 91.21% specific capacitance retention was reported, indicating excellent cyclic stability. In addition to this, the capacitance retention of the device was 83.5% after 5000 cycles, This study established the conversion of waste to efficient supercapacitor electrodes via eco-friendly, low-cost, two, simple process.