Investigation of the parameters affecting the morphology of zinc oxide (ZnO) nanoparticles synthesized by precipitation method

In this work, zinc oxide (ZnO) nanoparticles were synthesized using aqueous solutions of ZnSO4 and NaOH at ambient temperature and 70 °C. The nanoparticles synthesized at these two temperatures were identified and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential (ZP). SEM micrographs showed that temperature, method of mixing, and stoichiometric ratio could significantly affect the formation of particles of different sizes and morphology. Phase analysis of synthesized particles was performed by X-ray diffraction. The result showed that temperature had the tremendous potential to convert precursors into products to form a single-phase compound completely. These results were confirmed by the observed characteristic peaks in FTIR. The crystallite size was calculated using Scherer's equation and Rietveld analysis to investigate the effect of the calcination process on the crystal size of the synthesized particles. The results showed that the calcination process could significantly affect the crystal size of the synthesized particles. Both methods showed an increase in the average crystal size of zinc oxide particles after the calcination process. The absolute magnitude of the zeta potential for zinc oxide particles with a pyramidal rod morphology with an average diameter of 80–90 nm was 33.2 and for star-like morphology with an average diameter of 800–900 nm was 11.8.