Characterization and photocatalytic activity of ZnO nanoparticles by green synthesis method

Abstract

In this work, zinc oxide nanoparticles have been synthesized by green synthesis technique using sodium hydroxide and zinc nitrate, with and without calcination. In this research, Myrtus communis extract was used along with three different alkaline molar ratios (0.5 M, 1 M, and 2 M) to successfully synthesize ZnO nanoparticles (NPs) from the same precursor. In the calcined samples, this process was carried out at 800 °C. X-ray diffraction, scanning electron microscopy, and diffuse reflectance spectra were used to explore the structural, morphological, and optical features of ZnO nanoparticles. The XRD peaks confirm the successfully synthesized hexagonal wurtzite zinc oxide and are in full conformity with the published data of the JCPDS: 36–145. With high absorption peaks at about 370 nm wavelength, UV-Vis spectroscopy further supported the ZnO NPs' strong optical properties. Morphology and topography were discovered by SEM analysis and displayed the evolution of ZnO nanowires around 10 µm length with calcination. No nanowire formation was observed in the uncalcined samples. The results demonstrated that the degradation efficiency of ZnO nanoparticles is dependent primarily on the UV exposure time and morpholgy. When ZnO with 1 M NaOH calcined at 800 °C is used, the maximum MB degradation of about 99% is achieved. Methyl blue photodegradation follows the first-order Langmuir–Hinshelwood kinetic model.