Facile Synthesis of Nickel Oxide Nanoparticles and Its Application for Photocatalytic Degradation of Crystal Violet Dye
摘要
In this study, synthesis of nickel oxide nanoparticles was conducted employing a green route where leaf extracts of Camellia sinensis were used as a reducing agent, and the resultant nanoparticle was evaluated for its photocatalytic efficiency. Comprehensive characterization of the synthesized nanoparticle was performed using certain techniques like UV–visible spectroscopy, Fourier transmission infrared spectroscopy, x-ray diffraction, field emission scanning electron microscope, high-resolution transmission electron microscope, dynamic light scattering, and photoluminescence. The nanoparticles exhibited surface plasmon resonance peaks at 276 nm with a wide band gap value of 4.53 eV, confirming the crystalline nature, spherical morphology, and uniform size distribution of the synthesized nanoparticles. Five nanometers was found to be the average particle size as calculated by the Dynamic light scattering data. Fourier transmission infrared spectroscopy spectra revealed peaks at 617 cm⁻1 and 837 cm⁻1 that indicate the presence of a metal-oxide bond. By changing one parameter at a time, the synthesis of the nanoparticle procedure was standardized. The best parameters for the nanoparticles synthesis were 70 °C temperature, 25 mM nickel sulphate salt concentration, 11 pH, 20:30 volumetric ratio of nickel sulphate solution: reducing agent, and 30 min of incubation time. Holes or defects were identified in the structure of the nanoparticle using photoluminescence analysis. Such defects lower the recombination frequency for the charge carriers, thus enhancing the rate of photocatalysis. Upon UV irradiation, 98% degradation was observed for crystal violet dye within 50 min. The study further investigated the effects of initial concentrations of dye, pH, catalyst dosage, temperature, and point zero charge on photocatalytic performance.