Pseudocapacitive energy storage properties of rGO-WO3 electrode synthesized by electrodeposition

Abstract

This article focuses on the eco-friendly and facile fabrication of well-defined hybrid electrode favorable in supercapacitor devices with the aim of studying its electrochemical properties. Reduced graphene oxide/tungsten trioxide (rGO-WO3) hybrid electrode has been fabricated by a constant potential of −0.6 V on fluorine-doped tin oxide (FTO) substrate using one-pot electrodeposition technique combined with a subsequent calcination at 450 °C. The fabricated electrodes are examined by energy dispersive X-rays spectroscopy (EDX), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis to confirm the existence of each composition in the active material. The crystalline nature of tetragonal WO3 phase is verified by XRD analysis. The porous structures of WO3 nanoparticles with uniformly dispersed onto the rGO sheet are observed from scanning electron microscopy (SEM) examinations. FT-IR and Raman spectra confirm the characteristic peaks of GO, rGO, and interaction of WO3 with rGO. Besides, the electrochemical behaviors of the fabricated electrodes/electrolyte interface are broadly studied by several methods such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and Mott-Schottky in 1 M H2SO4 aqueous solution. Based on CV analysis, the rGO-WO3 electrode acts as better redox behavior in the potential between (−0.7 V) and (+0.2 V) than that of bare WO3 electrode, resulting in maximum specific capacitance value of 60.3 F/g at 5 mV/s. The GCD measurement displays a maximum specific capacitance value of 58.3 and 42.6 F/g at a current density of 1 A/g for rGO-WO3 and WO3 electrode, respectively. The n-type conductive characteristic of both electrodes is confirmed by Mott-Schottky measurement. The calculated donor density is 3.64 × 1020 cm−3 and 7.03 × 1020 cm−3 for WO3 and rGO-WO3, respectively. An equivalent circuit model is designed according to the Nyquist plot, and RCT value of the rGO-WO3 electrode is found to be 12.57 Ω. The synergetic interaction between carbon-based material and metal oxides opens up a way for forming a promising electrode to be used in energy storage devices.