Water-based synthesis of ZnO nanoparticles via decomposition of a ternary zinc complex containing Schiff-base, chelating, and Phen ligands

The recent environmental awareness has been the motivation for the growing preference for environmentally friendly and water-based systems in chemical synthesis. In the present work, ZnO nanoparticles were synthesized via a novel method without any water-insoluble compounds. At the first step, a binary Zn Schiff-base complex was prepared from sodium salicylaldehyde-5-sulfonate, L-alanine, and zinc acetate. Then, a ternary Zn complex containing the Schiff-base, chelating, and Phen ligands was synthesized from the as-synthesized binary Zn Schiff base and 1,10-phenanthroline monohydrate. This intermediate product showed high water solubility and long-term stability. Finally, ZnO nanoparticles were synthesized through the calcination of the ternary complex powder at 400, 500, and 600 degrees C. Combining X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) results, it was concluded that the samples contained the ZnO phase without any impurity phases, but Fourier transform infrared (FTIR) spectra implied the presence of a remaining impurity. According to the XRD, FTIR, and photoluminescence (PL) analyses, the as-synthesized samples differed in terms of the defect content and lattice strain. The sample calcined at 500 degrees C possessed the lowest defect content and lattice strain. Transmission electron microscopy (TEM) imaging revealed the formation of ZnO nanoparticles with particles sizes of <20, similar to 50, and similar to 100nm for samples heat-treated at the different temperatures.