Solar-assisted all-solid supercapacitors using composite nanostructures of ZnO nanowires with GO and rGO

Abstract

Solar-powered energy storage using integrated photo-supercapacitor (PSC) systems is drawing significant attention as a potential solution for the current energy problems. This work intends to prepare a facile, efficient, and low-cost two-electrode configuration all-solid-state PSC having zinc oxide nanowire (ZnO NW) composites with graphene oxide (GO) and reduced graphene oxide (rGO) as a remedy for the complexity and high-cost of the present PSC devices. The specific capacitance (C_p) and energy density of the GO/ZnO NW-based PSC increased 3.2 and 1.9 (@56 mA g⁻¹) times under UV illumination, respectively. Furthermore, the GO/ZnO NW-based PSC showed excellent stability for 5000 cycles with 100% capacitance retention and Coulombic efficiency. The superior performance and excellent stability due to the charge trap properties for the GO/ZnO NW-based PSC as compared to rGO/ZnO NW-based PSC have been confirmed using open circuit potential (V_OC) and low-temperature electron paramagnetic resonance (EPR) spectroscopy under UV on/off conditions. Hence, it has been concluded that GO/ZnO NW material and the proposed device configuration in this work are very favourable for future electronic applications.