Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis

Computational process design, optimization, growth, characterization and computational analysis of zinc oxide (ZnO) nanostructures grown on graphene using zinc acetylacetonate (Zn(acac)2) in the presence of hydrogen by ultrasonic spray pyrolysis were performed systematically. The dissociation of Zn...

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Main Author:	Ali Ibrahim, Amgad Ahmed
Format:	Thesis
Language:	English
Published:	2016
Subjects:	T58.5-58.64 Information technology
Online Access:	http://eprints.utm.my/id/eprint/92559/1/AmgadAhmedAliPMJIIT2016.pdf
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spelling	my-utm-ep.925592021-09-30T15:11:36Z Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis 2016 Ali Ibrahim, Amgad Ahmed T58.5-58.64 Information technology Computational process design, optimization, growth, characterization and computational analysis of zinc oxide (ZnO) nanostructures grown on graphene using zinc acetylacetonate (Zn(acac)2) in the presence of hydrogen by ultrasonic spray pyrolysis were performed systematically. The dissociation of Zn ions from vapour-phase Zn(acac)2 and its adsorption onto graphene oxide were studied using quantum mechanics approach involving the use of Density Functional Theory (DFT). The reaction energies were calculated, and the proposed reaction mechanism was well supported by a simulation of infrared properties. Next, Response Surface Methodology (RSM) was used to model and optimize the pyrolysis parameters by evaluating the nanostructure density, size and shape factor. The evolution of ZnO structures was well explained confirming that RSM is a reliable tool for the modelling and optimization of the pyrolysis parameters and prediction of nanostructure sizes and shapes. Finally, a computational analysis of the measured optical and charge transport properties of the grown nanostructures, i.e. Nanosphere Clusters (NSCs), Nanorods (NRs) and Nanowires (NWs) were developed. The calculated absorbance spectra based on the time-dependent DFT showed very close similarity with the measured behaviours. The atomic models and energy level diagrams were developed and discussed to explain the structural defects and band gap. As a conclusion it was found that the induced stress in the ZnO NSCs is the cause of gap narrowing between the energy levels. ZnO NWs and NRs showed homogeneous distribution of the Lowest Unoccupied Molecular Orbitals (LUMO) and Highest Occupied Molecular Orbitals (HOMO) orbitals all over the entire heterostructure which results to the reduction of the band gap. The calculated band gaps are confirmed to be in a good agreement with the experimental results. The electrical models and electrostatic potential maps were able to calculate the electron life time and to explain the mobility and diffusion behaviours of the grown nanostructures, respectively. 2016 Thesis http://eprints.utm.my/id/eprint/92559/ http://eprints.utm.my/id/eprint/92559/1/AmgadAhmedAliPMJIIT2016.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:106406 phd doctoral Universiti Teknologi Malaysia Malaysia-Japan International Institute of Technology (MJIIT)
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	T58.5-58.64 Information technology
spellingShingle	T58.5-58.64 Information technology Ali Ibrahim, Amgad Ahmed Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
description	Computational process design, optimization, growth, characterization and computational analysis of zinc oxide (ZnO) nanostructures grown on graphene using zinc acetylacetonate (Zn(acac)2) in the presence of hydrogen by ultrasonic spray pyrolysis were performed systematically. The dissociation of Zn ions from vapour-phase Zn(acac)2 and its adsorption onto graphene oxide were studied using quantum mechanics approach involving the use of Density Functional Theory (DFT). The reaction energies were calculated, and the proposed reaction mechanism was well supported by a simulation of infrared properties. Next, Response Surface Methodology (RSM) was used to model and optimize the pyrolysis parameters by evaluating the nanostructure density, size and shape factor. The evolution of ZnO structures was well explained confirming that RSM is a reliable tool for the modelling and optimization of the pyrolysis parameters and prediction of nanostructure sizes and shapes. Finally, a computational analysis of the measured optical and charge transport properties of the grown nanostructures, i.e. Nanosphere Clusters (NSCs), Nanorods (NRs) and Nanowires (NWs) were developed. The calculated absorbance spectra based on the time-dependent DFT showed very close similarity with the measured behaviours. The atomic models and energy level diagrams were developed and discussed to explain the structural defects and band gap. As a conclusion it was found that the induced stress in the ZnO NSCs is the cause of gap narrowing between the energy levels. ZnO NWs and NRs showed homogeneous distribution of the Lowest Unoccupied Molecular Orbitals (LUMO) and Highest Occupied Molecular Orbitals (HOMO) orbitals all over the entire heterostructure which results to the reduction of the band gap. The calculated band gaps are confirmed to be in a good agreement with the experimental results. The electrical models and electrostatic potential maps were able to calculate the electron life time and to explain the mobility and diffusion behaviours of the grown nanostructures, respectively.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Ali Ibrahim, Amgad Ahmed
author_facet	Ali Ibrahim, Amgad Ahmed
author_sort	Ali Ibrahim, Amgad Ahmed
title	Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
title_short	Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
title_full	Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
title_fullStr	Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
title_full_unstemmed	Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
title_sort	computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis
granting_institution	Universiti Teknologi Malaysia
granting_department	Malaysia-Japan International Institute of Technology (MJIIT)
publishDate	2016
url	http://eprints.utm.my/id/eprint/92559/1/AmgadAhmedAliPMJIIT2016.pdf
_version_	1747818603284004864

Computational prosess design, optimization and growth of zinc oxide nanostructures on graphene by ultrasonic spray pyrolysis

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