Electrochemical study of Ag₂O/MWCNTs composite electrode material for energy storage devices

Alternative energy sources are not merely clean and renewable but are extremely efficient in replacing fossil fuels and limiting global warming. Among energy storage devices supercapacitors offer high energy storage and fast charge–discharge process with good rate capability. This research is focused on developing a nanocomposite electrode for supercapacitors to enhance the lifetime and energy storage capacity. Ag₂O nanoparticles anchored multiwalled carbon nanotubes electrode material Ag₂O/MWCNT is synthesized by hydrothermal method. XRD analysis confirms the hexagonal phase of MWCNTs and the cubic phase of Ag₂O. SEM micrographs show the encapsulation of metal nanoparticles on MWCNTs surface. The absorbance spectra indicate the shifting of the characteristic absorption peak of MWCNTs towards a longer wavelength. Tauc plot reveals a redshift in bandgap from 2.8 eV to 2.6 eV. The Raman spectra reveal the presence of D, G, and 2D bands, indicating defective states, while the observed shifting of bands demonstrates the successful synthesis of Ag₂O/MWCNTs. The electrochemical measurements in a 1 M solution of KOH at a scan rate of 10 mVs⁻¹ exhibit a specific capacitance of 376 F g⁻¹. GCD curves offer a specific capacitance of 312 F g⁻¹ and an energy density of 43.33 Wh kg⁻¹ at 1 A g⁻¹ with a power density of 500 W Kg⁻¹. Moreover, the impedance analysis of Ag₂O/MWCNTs electrode shows a charge transfer and electrolyte solution resistance of 14.28 Ω and 2.75 Ω respectively as determined from the Nyquist plot. The electrochemical performance suggests that the Ag₂O/MWCNTs nanocomposite holds significant potential to be used as an electrode material for energy storage applications.