Sustainable Synthesis and Multifunctional Applications of NiO Nanoparticles in Photocatalysis and Electrochemistry

In this work, the synthesis of nickel oxide (NiO) using nickel acetate through a green synthetic approach has been reported. The green synthesis approach was employed for the synthesis of NiO nanoparticles as it employs plant-based precursors and mild reaction conditions, reducing environmental impact and avoiding the use of hazardous chemicals while maintaining high efficiency and scalability. The structural, spectral and morphological properties of the synthesized NiO nanoparticles were characterized using Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Further, Electrochemical Impedance Spectroscopy (EIS) studies like cyclic voltammetry and Nyquist plots were utilized for electrochemical studies. The energy storage behavior of the synthesized NiO nanoparticles was studied by Galvanostatic Charge-Discharge (GCD) curves. Finally, the NiO nanoparticles were subjected to photocatalytic activity on exposure to UV light. The nanoparticles exhibited a cubic phase with crystallite sizes matching well between XRD and TEM results. Electrochemical studies demonstrated excellent cycling stability, with more than 90% of the initial capacitance retained even after 2000 charge–discharge cycles. Photocatalytic activity of the NiO nanoparticles achieved a degradation efficiency of 71.62% for Fast Blue dye under UV light exposure for 120 min, indicating their significant potential for environmental applications. Additionally, the energy bandgap of the NiO nanoparticles was determined to be 3.57[Formula: see text]eV.