Authors:	Sarif, Massih Ahmad
Advisor:	Tremel, Wolfgang
Title:	Synthesis of Various Metal Oxides by Different Synthetic Methods
Online publication date:	10-Feb-2022
Year of first publication:	2022
Language:	german
Abstract:	The potential applications of nanoparticles cover an enormous spectrum. The present work addresses the synthesis of nanoparticles using different synthetic methods and their potential fields of application. The first section of the thesis deals with the synthesis of perfectly shaped CoO nanooctahedra in a classical batch synthesis. The preparation of the nanoparticles first required optimization of the synthesis conditions, especially with respect to the ligand concentrations, ligand ratios, and reaction temperature. X-ray and electron diffraction were used to establish the crystal structure of the CoO nanooctahedra. Transmission electron microscopy was used to demonstrate the octahedral morphology of the particles. X-ray spectroscopic and magnetic studies confirmed the formation of phase-pure CoO and its surface chemistry. Molecular dynamics simulations were performed based on the experimental data. This showed that the binding energy of the surface ligands used for synthesis was lowest at a ratio of 1:1 (oleic acid/oleylamine). Based on the experimental and simulated data, a mechanism for the formation of the octahedral nanoparticles was elucidated. The morphology of the particles had a crucial impact on the catalytic activity in anodic oxygenation during electrochemical water splitting. The second section of the dissertation deals with the synthesis of CeO2 nanoparticles in segmented flow as well as batch processes. Electron microscopic, thermal, vibrational spectroscopic and sorption studies showed no significant differences in terms of particle surface area or morphology. For segmented flow reactions, the reaction time was significantly reduced, and the yield was significantly increased. Haloperoxidase activity was detected by phenol red assay. The CeO2 nanoparticles were then used to prepare polycarbonate nanocomposites. The nanocomposites showed up to 85% reduction in biofilm formation. In addition, the formation of the virulence factor pyocyanin, which is directly linked to the quorum sensing system of bacteria, was reduced by 55%. In the third part of the work, a rapid microfluidic synthesis of NaCrO2 particles on a large scale was elaborated. The structure of NaCrO2 particles and their surface structure were determined by X-ray diffraction and X-ray spectroscopy studies. Investigations by 1H and 23Na nuclear magnetic resonance spectroscopy, Raman spectroscopy, thermal analysis, and transmission electron microscopy provided information about the formation mechanism of the NaCrO2 particles. Submicrometer-sized micelles were formed by water-in-oil emulsions, acting as microreactors in the synthesis and allowing mixing of the reaction components at the molecular level. When the micelle-stabilized mixtures were heated, the product NaCrO2 was formed after a short annealing time and at moderate temperatures. The microfluidic synthesis of NaCrO2 was used for the synthesis of other layered oxides with the formular NaMO2 such as NaAlO2, NaFeO2 and NaCoO2. It offers the possibility to produce potential or already commercially used battery materials in very short reaction time in large quantities and with constant quality.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-6668
URN:	urn:nbn:de:hebis:77-openscience-9e685f92-e1cc-4b14-b8ad-a68e378244ff9
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	http://rightsstatements.org/vocab/InC/1.0/
Extent:	ii, 147 Seiten, Illustrationen, Diagramme
Appears in collections:	JGU-Publikationen