Defense Date

4-14-2005

Graduation Date

Spring 2005

Availability

Immediate Access

Submission Type

dissertation

Degree Name

PhD

Department

Chemistry and Biochemistry

Committee Chair

Shahed U. M. Khan

Committee Member

Jeffry D. Madura

Committee Member

Jeffrey D. Evanseck

Committee Member

David W. Wright

Keywords

semiconductors, self-driven photoelectrochemical cells (PEC), p-type iron(III) oxide, carbon-modified n-type titanium dioxide, hydrogen generation

Abstract

My Ph.D. Dissertation describes (1) the influence of metal dopants on the spray pyrolytic synthesis of p-type and n-type iron(III) oxide thin film semiconductors, (2) the fabrication of carbon-modified (CM) n-type titanium dioxide, and (3) various self-driven photoelectrochemical cells (PEC) for water splitting. (1) Stable thin films of Fe2O3 was the first goal pursued in this work. Various metal dopants were investigated to ascertain their viablity as good dopant for iron(III) oxide. These metals included copper, zinc, and magnesium. This was follwed by investigating metals that could improve the conductivity of n-type iron(III) oxide, which included indium, iodine, manganese, and calcium. Research showed that zinc improved p-type characteristics the best, and considerably improved stability of p-type iron(III) oxide in acidic media. Indium-doped n-type iron(III) oxide showed improvement in photocurrent response over naturally-doped iron(III) oxide; however, there was a loss in the onset potential, which proved vital for developing a self-driven PEC. Importantly, the use of 1-pentanol as the spray solution solvent instead of ethanol improved the onset potential and photoresponse of n-type iron(III) oxide which helped to fabricate a self-driven p-type/n-type iron(III) oxide PEC for water splitting. (2) Carbon-modified n-type titanium dioxide electrodes were found to be extremely valuable towards fabrication of self-driven water spliting PEC, because the addition of carbon into the titanium dioxide crystal structure provided it with the ability to absorb light much further into the visible spectrum. Unmodified titanium dioxide can only absorb ~13% of the total solar power (100 mW/cubic cm) of Air Mass (AM) 1.5; in other words wavelengths of light from ultraviolet to 414 nm. Carbon modification of n-type titanium dioxide allows it to absorb upto 535 nm, or ~ 30% of the total solar power. (3) The most important part of this work is the fabrication of a self-driven PEC for water splitting using zinc-doped p-type iron(III) oxide and naturally-doped n-type iron(III) oxide; carbon-modified n-type titanium dioxide and zinc-doped p-type iron(III) oxide; and p-type galliun indium phosphide and carbon-modified n-type titanium dioxide.

Format

PDF

Language

English

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