Surfactant assisted sonochemical synthesis of Bi2WO6 nanoparticles and their improved electrochemical properties for use in pseudocapacitors

Abstract

Hexamethylenetetramine (HMT) assisted Bi₂WO₆ nanoparticles were successfully synthesized by a sonochemical method for use as negative electrodes for pseudocapacitors. The effect of different concentrations of HMT on the structural, morphological, compositional and electrochemical properties was investigated. Detailed structural investigations were performed using Rietveld analysis and the formation of a single phase Bi₂WO₆ with orthorhombic russellite structure was deduced. The compound formation temperature of Bi₂WO₆ was analyzed using differential scanning calorimetry. The presence of possible functional groups was revealed by Fourier transform infrared spectroscopy analysis. A decrease in particle size was observed due to the effect of surfactant. The electrochemical performance of the materials was assessed using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS). The electrochemical studies showed an enhanced specific capacitance of 708 F g⁻¹ for Bi₂WO₆ in the presence of 0.01 mol HMT as compared to 304 F g⁻¹ which was obtained without surfactant. The EIS spectral analysis suggested that the surfactant assisted Bi₂WO₆ has a lower charge transfer resistance (12.4 Ohm for 0.01 mol HMT) compared with the pristine (32.77 Ohm) material. The electrochemical analysis proved the vital role played by HMT in enhancing the specific capacitance of Bi₂WO₆ material.