Biosynthesis of rGO and Ag-rGO nanocomposites for symmetrical supercapacitor electrode

The present work demonstrates a green reduction method using Urtica dioica L. (Kandali) leaf extract to convert graphene oxide (GO) into reduced graphene oxide (rGO) at a low temperature (70 °C). Likewise, a similar method has been employed to prepare silver (Ag)-rGO nanocomposites (NCs). As-synthesized rGO and NCs have been characterized using various structural and morphological characterization techniques to confirm the formation of NCs. The noticeable reduction in oxygen-containing functional groups from GO to rGO, along with the Raman and EDX results, confirms the successful synthesis of rGO and the NCs. Additionally, the synthesized rGO and Ag-rGO NCs have been examined as electrode materials for symmetrical supercapacitor (SSC). The electrochemical performance has been evaluated at a current density of 2 A/g; the specific capacitance is found to be ∼ 240.2 F/g for rGO and 350 F/g for Ag-rGO NCs. The power densities rGO and Ag-rGO NCs’ are obtained 859.70 W/kg and 1558.47 W/kg, respectively, and their energy densities are found 16.34 Wh/kg and 23.81 Wh/kg. Excellent capacitance retention is achieved ∼93.8% in cycling studies at 100 mV/s for NCs after 2000 cycles. Thus, it has been evident that an environmentally friendly method has been successfully utilized to create rGO and Ag-rGO NCs in large quantities with promising electrochemical performance of SSCs.