Nanostructured Ag/NiO composites for supercapacitor and antibacterial applications, and in-silico theoretical investigation

Abstract

In the current study, Ag/NiO nanocomposite performance, antibacterial properties, and in-silico theoretical method were examined utilizing Withania somnifera leaf extract. The ultraviolet–visible spectra showed distinct absorption peaks at 295 and 423 nm, confirming the presence of Ag and NiO. Morphological studies (scanning electron microscopy and high-resolution transmission electron microscopy) revealed mingled hexagonal and spherical structure, and energy-dispersive X-ray spectroscopy showed elemental composition of Ag/NiO. The crystal structure of Ag/NiO was confirmed by X-ray diffraction analysis and structural parameters were studied through Rietveld refinement analysis. Fourier transform infrared spectroscopy identified alkaloids as the main compounds responsible for the reduction of Ag and NiO. The occurrence of Ag, Ni, and O with compressed phytochemicals was identified using X-ray photoelectron spectrometry. The electrochemical performance and antimicrobial activities of Ag/NiO were investigated. The as-prepared Ag/NiO electrode exhibited specific capacitance of 872 F/g at a scan rate of 5 mV/s and revealed good cyclic retention of about 89.2 % even after 5000 cycles. Furthermore, admirable electrochemical properties of Ag/NiO provided an asymmetrical supercapacitor device with energy density of 46 Wh/kg and power density of 3501 W/kg. This indicates good prospects for utilization of biomass-derivable electrode material for energy storage applications. In addition, Ag/NiO had significant inhibitory effects (zone of inhibition: 15.4 mm, minimum inhibitory concentration: 12.5 μg/mL) against the human pathogen Klebsiella pneumoniae. The high probability of antibacterial action of the obtained complex was theoretically studied and the results correlated with experimental study.