Bioinspired synthesis of nickel oxide nanoparticles as electrode material for supercapacitor applications

Nickel oxide nanoparticles (NiO NPs) were synthesized by adopting green route with a nontoxic aqueous phytoextract of guava leaves for their application as supercapacitor electrodes. The characteristic UV absorption peak for NiO NPS was observed at 266 nm. X-ray diffraction (X-RD) study confirms the crystalline nature of biosynthesized nanoparticles with cubic face-centered crystal structure. Coral-like shape of nanostructures of NiO is demonstrated by scanning electron microscopy (SEM). Biosynthesized NiO nanoparticles are further characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and differential thermal analysis (DTA). The electrochemical properties and cycle performance of supercapacitor device using NiO nanoparticles as electrode material were investigated by cyclic voltammetry with different concentrations of aqueous potassium hydroxide (KOH) electrolyte. The NiO NPs electrode exhibited specific capacitance of 85.31 F/g in the potential window of 0.8 V at the scan rate 2 mV/s with 5 M KOH electrolyte.