Exploring the synergistic effect of temperature on hydrothermally synthesized tungsten oxide (WO3) nanostructures and its role in asymmetric liquid-state hybrid supercapacitors

The objective of this study was to produce non-uniform nanostructures (NSs) with different crystalline structures of the tungstate oxide (WO3) using the simple hydrothermal method for the supercapacitor application to overcome the critical energy crisis. In these aspects, the prepared WO3-NSs have been thoroughly examined using various physio-chemical methods likely Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Raman spectroscopy, Scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The supercapacitive characteristics of WO3-NSs Ni-foam (NF) based electrodes were studied using an aqueous 2 M KOH electrolyte. According to the findings, the W3-NF electrode exhibits a higher specific capacitance (Cs) of 750 F/g and capacity (Csp) of 94 mAh/g with moderate specific energy (Ed), power densities (Pd) of 22 Wh/kg, and 600 W/kg at 5 mA/cm2, as well as capacitive retention of 91% after 5000 cycles. Furthermore, an asymmetric liquid state hybrid device (ASH) was fabricated using WO3-NF and GO-NF as the positive and negative materials respectively. The ASH device delivers a maximum Ed of 32 Wh/kg and Pd of 1170 W/kg while maintaining capacitive retention of 90% over the 4000 cycles of charging and discharging. Therefore, the findings have sparked significant interest in exploring the synthesis, and performance evaluation of WO3-NSs for SCs applications.