Abstract

In the current work, reduced graphene oxide (x = 5, 10, and 15 wt%) decorated over cesium oxide@cobalt oxide nanostructures (NS) was synthesized by a simple chemical precipitation method. The hybrid NS was characterized by XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy), TEM (transmission electron microscopy), TGA (thermogravimetric analysis), XPS (X-ray photoelectron spectroscopy), BET (Brunauer-Emmett-Teller), UV-visible analytical tools. XRD analysis of reduced graphene oxide15wt%:cesium oxide@cobalt oxide NS revealed orthorhombic/monoclinic crystal structure and average crystallite size decreases with an increase in the concentration of reduced graphene oxide on cesium oxide@cobalt oxide NS. Small flake/ plate/petal like morphology of reduced graphene oxide5wt%-15wt%:cesium oxide@cobalt oxide NS was observed by FESEM images with irregular distribution of the nanoparticles (NPs). The redshift in optical absorption peaks resulted from UV-visible studies with a decrease in optical band gap and an increase in the concentration of reduced graphene oxide on cesium oxide@cobalt oxide NS. Supercapacitor performances of undoped cesium oxide@cobalt oxide NS and reduced graphene oxide15 wt%: cesium oxide@cobalt oxide NS examined by cyclic voltammetry (CV), galvanostatic charge discharge cycles (GCD), electrochemical impedance studies (EIS) in 3 M KOH aqueous electrolyte. The reduced graphene oxide15 wt%: cesium oxide@cobalt oxide NS exhibited maximum specific capacitance (SC) of 740 F/g (scan rate of 100 mV/s) with capacitive retention of 95.4 % at current density of 1A/g after 5000 cycles. Photocatalytic dye degradation of Alizarin Red S (ARS) dye under visible light for the reduced graphene oxide15wt%:cesium oxide@cobalt oxide NS showed a degradation efficiency of 98.3 % with a rate constant of 3.9 x 10_2. However, undoped (cesium oxide@cobalt oxide) NS showed degradation efficiency of 77.1 % with a rate constant of 2.4 x 10_2. The undoped and reduced graphene oxide15 wt%: cesium oxide@cobalt oxide NS showed 74.1 % and 95.9 % catalyst reusage after 5 successive cycles. The synthesized reduced graphene oxide x: cesium oxide@cobalt oxide NS is a promising electrode material for supercapacitor and photocatalytic dye degradation.