Effect of nitric acid on hydrothermal synthesis of Bi2WO6 nanosheets for supercapacitor application

초록

This research investigates the effects of nitric acid (HNO3) treatment on the structural, morphological, and electrochemical properties of Bi2WO6 nanosheets. The monoclinic structure of Bi2WO6 was verified by the X-ray diffraction (XRD) analysis. Morphological observations were made using Field emission scanning electron microscopy (FE-SEM). TEM, HRTEM and SAED confirm the formation of highly crystalline Bi2WO6 nanosheets with controlled morphology influenced by HNO3 treatment. The FTIR spectrum showed absorption peaks 450 cm-1 and 1000 cm-1, due to the stretching and bending vibrational frequencies of Bi-W-O bonds. The Raman spectroscopy showed an active W-O stretching mode at 889 cm-1. In a 3 M KOH aqueous electrolyte, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the samples' electrochemical performance. Compared to earlier reported Bi2WO6 electrodes (generally 150-350 Fg-1), the HNO3 treated Bi2WO6 nanosheets exhibits relatively enhanced performance, achieving 422-449 F g(-)1, resistance of 0.91 Omega, coulombic efficiency was 99.9%, and remarkable cycling stability (93.9% retention even after 5000 charge-discharge cycles), comparable with high-performing metal oxide supercapacitor electrodes.