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Permanent link (DOI): https://doi.org/10.7939/R35X25J54
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Transition Metal Oxide Materials for Electrocatalytic and Photocatalytic Water Splitting Open Access
- Other title
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Bau, Jeremy A
- Supervisor and department
Buriak, Jillian M (Chemistry)
- Examining committee member and department
Bergens, Steven H. (Chemistry)
Deng, Zhifeng (Chemistry, Western University)
Wang, Xihua (Electrical and Computer Engineering)
McCreery, Richard L. (Chemistry)
Department of Chemistry
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
As the developing world industrializes, humanity needs to produce a greater fraction of its energy via renewable resources in order to alleviate the scarcity of fossil fuels as well as environmental damage from the exhaust of these fuels. However, renewable sources of energy tend to be intermittent in nature and therefore require a method to store generated energy for use at a later time. Hydrogen gas is a promising potential fuel because it can be produced from water with oxygen gas as a byproduct, resulting in an environmentally-friendly production-consumption cycle with water as the product upon combustion. This thesis presents two different approaches to hydrogen generation from water – using light and electricity – with earth-abundant metal oxide catalysts.
A dual-semiconductor photocatalyst consisting of α-Fe2O3 and CuFe2O4 semiconductor materials in close contact was prepared by first templating iron oxide precursors on sugarcane leaf followed by functionalization of the resulting α-Fe2O3 surface with copper nanoparticles and high-temperature annealing. Nanoparticle catalysts were further loaded onto the surface of the combined α-Fe2O3/CuFe2O4 heterostructure. Investigation of the CuFe2O4 material revealed that it was a poor semiconductor that could evolve hydrogen independently but at low rates.
A novel nickel-iron oxide phase with rock-salt structure was synthesized via thermal decomposition of mixed nickel and iron oleate complexes. Despite the natural instability of bivalent iron in rock-salt crystal structures, the single-crystal [Ni,Fe]O nanoparticles were stable even under ambient conditions for long periods of time, even upon thermal treatment at 200 °C. Shape control of the nanoparticles could be achieved via modification of the synthetic conditions, resulting in a variety of shapes including cubes, stars, and spheres. The composition of the nanoparticles could also be controlled yielding a wide composition range of nickel iron oxide rock-salt nanocrystals. The surface of the nanoparticles was determined to contain trivalent iron and an amorphous structure unique from the bulk.
The nickel-iron oxide nanoparticles were applied for water oxidation after integration onto tin-doped indium oxide and fluorine-doped tin oxide electrode surfaces. The functionalization was accomplished using UV light irradiation, which resulted in the formation of durable nanoparticle films that withstood the stresses of water oxidation. Electrochemical studies suggested that catalytic activity arose from the surface of the nanoparticles, suggesting that the [Ni,Fe]O phase did not participate in water oxidation. Nonetheless, by giving rise to the catalytic surface layer, [Ni,Fe]O was found to be important for water oxidation as activity was reduced when the phase was lost via heating.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
J.A. Bau, P. Li, A.J. Marenco, S. Trudel, B.C. Olsen, E.J. Luber, J.M. Buriak, Chem. Mater. 2014, 26(16), 4796-4804.
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