Facile Chemical Synthesis of silver Tungstates and silver Tungsten/Reduced Graphene Oxide as High Performance Supercapacitor

Nanosilver tungstate (Ag2WO4) were synthesized by a chemical precipitation reaction in aqueous ambient involving direct addition of silver ion solution to the solution of tungstate reagent. Optimization of the synthesis procedure was carried out using Taguchi robust design as statistical method. In order to controllable, simple and fast synthesis of Ag2WO4 nanoparticles, effects of some synthesis conditions such as reagents concentrations (i.e., silver and tungstate ions), flow rate of silver feeding and temperature of the reactor on the size of synthesized Ag2WO4 were investigated by the aid of an orthogonal array (OA9). Chemical composition and microstructure of the prepared Ag2WO4 were characterized by means of XRD, SEM, FT-IR spectroscopy and UV-Vis spectroscopy. a composite of reduced graphene oxide (RGO) with silver tungstate (Ag2WO4) was prepared using a sonochemical method. The prepared Ag2WO4/RGO samples were assessed through FE-SEM to obtain morphological information. The resulting composite (Ag2WO4/RGO) was evaluated as a candidate for building supercapacitor electrodes. In this line the electrochemical performance of the tested materials were studied through cyclic voltammetry (CV), galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), and continues cyclic voltammetry (CCV). The electrochemical tests were performed using 2 M H2SO4 solutions as the electrolyte. The evaluations on Ag2WO4/RGO-based electrodes revealed the material to have a specific capacitance of 534 F g-1 at a scan rate of 5 mV s-1, an energy density of 68 W h kg-1, and a high rate capability. Continues cyclic voltammetry evaluations using Ag2WO4/RGO-based electrodes proved the electrodes to be capable of maintaining almost 102.1% of its initial SC after 5000 cycles. Based on the electrochemical evaluations the synthesized nanocomposite was proven to possess the merits of both of its ingredients