The study of transparent hematite films using ultrafast and Raman spectroscopies

dc.contributor.advisorDiale, M. (Mmantsae Moche)
dc.contributor.coadvisorKruger, T.P.J. (Tjaart)
dc.contributor.emailsipho.congolo@gmail.comen_US
dc.contributor.postgraduateCongolo, Sipho
dc.date.accessioned2024-08-26T12:32:17Z
dc.date.available2024-08-26T12:32:17Z
dc.date.created2020-04
dc.date.issued2019-11
dc.descriptionDissertation (MSc (Physics))--University of Pretoria, 2019.en_US
dc.description.abstractHematite (Fe2O3) is a promising photoanode material that is being studied immensely for its application in solar water splitting to produce hydrogen and oxygen as fuels. It has attractive properties such as a narrow bandgap that allows for absorption of visible light, it is earth-abundant and is an easily processable photocatalytic material. In this study, we report on hematite thin films prepared by spray pyrolysis on fluorine-doped tin oxide (FTO) coated glass substrates. The samples were prepared by spray pyrolysis and treated with tetraethoxysilane as well as post-annealed. We employed ultrafast transient absorption spectroscopy and high-resolution confocal Raman microscopy for analysis of the hematite thin films. For all the films, Raman spectroscopy confirmed the characteristic spectrum of the hematite. The high-resolution Raman mapping showed a uniform intensity over the analyzed areas which suggests a uniform coating of the hematite films on the FTO substrates. Ultrafast transient absorption spectroscopy was used to investigate the effect of three experimental parameters; the effect of the spray volume, tetraethoxysilicate treatment of the hematite and post-annealing at 500 ºC for 2 hours with 10 ºC/min ramping. All three parameters gave a positive result. Ultrafast transient absorption spectroscopy indicates that all three experimental parameters slowed down electron-hole recombination. Global analysis of the difference absorption data resolved the spectra and associated decay lifetimes of three distinct processes, operating on the ultrafast, tens of picoseconds and hundreds of picoseconds timescales. Thus, understanding these properties will aid in the engineering of this material to prolong recombination and, as a result, improve its solar to hydrogen conversion efficiency in photoelectrochemical cells.en_US
dc.description.availabilityUnrestricteden_US
dc.description.degreeMSc (Physics)en_US
dc.description.departmentPhysicsen_US
dc.description.facultyFaculty of Natural and Agricultural Sciencesen_US
dc.identifier.citation*en_US
dc.identifier.otherA2020en_US
dc.identifier.urihttp://hdl.handle.net/2263/97861
dc.language.isoenen_US
dc.publisherUniversity of Pretoria
dc.rights© 2021 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.
dc.subjectUCTDen_US
dc.subjectHematiteen_US
dc.subjectSpray pyrolysisen_US
dc.subjectConfocal Raman microscopyen_US
dc.subjectPump-probeen_US
dc.subjectTransient absorption spectroscopyen_US
dc.titleThe study of transparent hematite films using ultrafast and Raman spectroscopiesen_US
dc.typeDissertationen_US

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