Green Synthesis of Silver-Doped NiO Nanoparticles for Photocatalytic and Electrochemical Sensor Applications from Neem Leaf Latex

Neem (Azadirachta indica) leaf extract was used to create pure NiO and Ag-doped NiO nanoparticles (Ag-NiO NPs) of 1, 3, and 5 mol% by solution combustion method at 400 °C and calcining at 1000 °C for two hours. The synthesized Ag-NiO NPs were comprehensively characterized using various analytical techniques, including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM/HRTEM), Selected Area Electron Diffraction (SAED) and UV-diffuse reflectance spectroscopy (UV-DRS). Powder X-ray diffraction (PXRD) analysis confirmed their cubic crystal structure with a space group of Fm-3m. The average crystallite size of 25 nm. The bandgap energy for pure NiO, 1%, 3%, and 5% Ag doped NPs is to be 4.08, 4.05, 3.96, and 3.84 eV. The 3% Ag-doped NiO showed strong photocatalytic activity in breaking down Fast Blue (FB) and Acid Orange Red (AOR) dyes, with absorption peaks at 622 nm and 484 nm, respectively. After 120 min of UV light exposure, a significant reduction in dye concentration was observed, confirming the material’s effectiveness for photocatalytic applications. Excellent redox potential output was determined by cyclic voltammetry (CV) in an electrochemical evaluation of the produced material using graphite electrode paste in 1 M KOH electrolyte. Electrochemical impedance spectroscopy (EIS) research has demonstrated that the decreased charge transfer resistance of Ag-NiO NPs is responsible for their improved behaviour. After computation, it was discovered that the Ag-NiO NPs -specific capacitance values were 125.7 Fg⁻¹ at a scan rate of 50 mVs⁻¹. The paracetamol and penegra materials were effectively sensed by the prepared carbon paste electrode of Ag-NiO NPs (3 mol%) as revealed by cyclic voltammetric and EIS studies. All the above results show that the synthesized Ag-NiO (3%) NPs can be a potential candidate for waste water treatment and electrochemical sensor applications.