Studies in the photoelectrochemistry of bismuth vanadate using scanning electrochemical microscopy

dc.contributor.advisorBard, Allen J.
dc.creatorPark, Hyun Seoen
dc.date.accessioned2014-03-04T18:01:10Zen
dc.date.issued2012-12en
dc.date.submittedDecember 2012en
dc.date.updated2014-03-04T18:01:11Zen
dc.descriptiontexten
dc.description.abstractPhotoelectrochemical studies were performed on bismuth vanadate (BiVO₄) to understand chemical and physical properties of the photocatalysts, and to improve the photoactivity for water oxidation. Scanning electrochemical microscopy (SECM) was used to screen various dopants for BiVO₄, to calculate the photoconversion efficiencies to chemical energy at BiVO₄ electrodes, and to study the water oxidation intermediate radicals at the surface of BiVO₄. Tungsten and molybdenum doped BiVO₄ (W/Mo-BiVO₄) shows a photocurrent for water oxidation that is more than 10 times higher than undoped BiVO₄. Photoelectrochemical measurements and material analysis were done to discuss the factors that affect performance of BiVO₄. Finite elements analysis was also performed to explain the electron-hole transport and electrochemical reactions at W/Mo-BiVO₄ electrodes in solutions. Addition of conductive or electron accepting materials, e.g. reduced graphene oxide, into BiVO₄ was tried to study the electron-hole transport phenomena in the metal oxide electrodes. Surface adsorbed radicals produced during the water oxidation at W/Mo-BiVO₄ were interrogated by using SECM that the surface coverage and decay kinetics of adsorbed hydroxyl radicals at W/Mo-BiVO₄ were measured. The quantum efficiencies of the injected photon conversion to chemical energy were obtained from the photoelectrochemical measurements by using SECM. SECM techniques and finite elements analysis were also used to measure the faradaic efficiency of water oxidation at W/Mo-BiVO₄ under irradiation. Finally, unbiased water splitting to generate hydrogen and oxygen from water splitting only using photon energy at W/Mo-BiVO₄ electrodes was demonstrated in a dual n-type semiconductor or Z-scheme device.en
dc.description.departmentChemistryen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/23396en
dc.subjectElectrochemistryen
dc.subjectPhotochemistryen
dc.subjectPhotoelectrochemistryen
dc.subjectWater splittingen
dc.subjectBismuth vanadateen
dc.titleStudies in the photoelectrochemistry of bismuth vanadate using scanning electrochemical microscopyen
dc.typeThesisen
thesis.degree.departmentChemistryen
thesis.degree.disciplineChemistryen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen

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