Tailoring the multifunctional properties of hydrothermally synthesized reduced graphene oxide/tungsten oxide supported nanorods to enhance the electrochemical and water-splitting activities

Abstract

Herein, we employ the synergistic effect and better conductivity of graphene oxide (GO) and reduced graphene oxide (rGO) to boost the energy storage capacity and electrical conductivity of tungsten oxide (WO3) nanomaterials. The structural analysis of the WO3 and its composites revealed the presence of a monoclinic phase with a periodic arrangement. However, the field emission scanning electron microscopy revealed the nanorod-shaped morphology for WO3 and the nonuniform interconnected nanorod nanosheet-like morphology for composites. The identification of functional groups and stretching–bending vibrations of W–O, CO WO, and C–C bonds are revealed by FT-IR and Raman spectroscopy. Additionally, the transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the morphological, structural, and electronic states of hybrid rGO/WO3 nanostructures. The supercapacitive properties and electrocatalytic activity of WO3, GO/WO3, and rGO/WO3–nickel foam (NF) electrodes were investigated using a 2 M KOH via an three-electrode system in the desired potential window. As a result, the rGO/WO3 electrode exhibited promising electrochemical performance with a large specific capacity, 135 mAh/g (972 F/g) with high energy (ED), and power density (PD) of 33 Wh/kg and 1100 W/kg at 5 mA/cm2, and excellent retention of 92 % after 5000 CV cycles. However, the hybrid device is fabricated using rGO/WO3//rGO-NF as electrodes and exhibited a high specific capacity (78 mAh/g and 177 F/g at 5 mV/s), decent cycling stability (85 % after 5000 cycles), and high ED/PD (33 Wh/kg /1166 W/kg) respectively. Moreover, the electrocatalytic activity of WO3, GO/WO3, and rGO/WO3 electrodes was studied using 2 M KOH respectively. The superior electrochemical activities such as overpotential, Tafel slope, and the good electrochemical surface area (ESCA) of 328 mV, 95.5 mV/dec, and 38.2 cm2 with good stability were observed for rGO/WO3 electrode. The proposed asymmetric design provides promising material for developing next-generation energy storage devices for various portable electronic systems and water-splitting activity.