Influence of Synthesis Conditions on the Properties of Zinc Oxide Obtained in the Presence of Nonionic Structure-Forming Compounds

This work investigated the influence of synthesis conditions, including the use of nonionic structure-forming compounds (surfactants) with different molecular weights (400-12,600 g/mol) and various hydrophilic/hydrophobic characteristics, as well as the use of a glass substrate and hydrothermal exposure on the texture and structural properties of ZnO samples. By X-ray analysis, it was determined that the synthesis intermediate in all cases is the compound Zn-5(OH)(8)(NO3)(2)center dot 2H(2)O. It was shown that thermolysis of this compound at 600 degree celsius, regardless of the physicochemical properties of the surfactants, leads to the formation of ZnO with a wurtzite structure and spherical or oval particles. The particle size increased slightly as the molecular weight and viscosity of the surfactants grew, from 30 nm using Pluronic F-127 (MM = 12,600) to 80 nm using Pluronic L-31 (MM = 1100), PE-block-PEG (MM = 500) and PEG (MM = 400). Holding the pre-washed synthetic intermediates (Zn-5(OH)(8)(NO3)(2)center dot 2H(2)O) under hydrothermal conditions resulted in the formation of hexagonal ZnO rod crystal structures of various sizes. It was shown that the largest ZnO particles (10-15 mu m) were observed in a sample obtained during hydrothermal exposure using Pluronic P-123 (MM = 5800). Atomic adsorption spectroscopy performed comparative quantitative analysis of residual Zn2+ ions in the supernatant of ZnO samples with different particle sizes and shapes. It was shown that the residual amount of Zn2+ ions was higher in the case of examining ZnO samples which have spherical particles of 30-80 nm. For example, in the supernatant of a ZnO sample that had a particle size of 30 nm, the quantitative content of Zn2+ ions was 10.22 mg/L.

Automated summary

This work investigated the influence of synthesis conditions and hydrothermal exposure on the texture and structural properties of ZnO samples. It was found that regardless of the surfactant used, ZnO with a wurtzite structure and spherical or oval particles can be formed. The particle size slightly increases with the molecular weight and viscosity of the surfactants. Hydrothermal exposure results in the formation of hexagonal ZnO rod crystal structures of various sizes. ZnO samples with spherical particles of 30-80 nm have higher residual Zn2+ ion content.