ORCID Identifier(s)

0000-0002-2262-6181

Graduation Semester and Year

2019

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry

Department

Chemistry and Biochemistry

First Advisor

Krishnan Rajeshwar

Second Advisor

Robin Macaluso

Third Advisor

Daniel W Armstrong

Fourth Advisor

Peter Kroll

Abstract

Photoelectrochemical (PEC) water splitting using inorganic semiconductors is a promising approach to convert sunlight into sustainable fuels. However, many scientific and engineering challenges need to be overcome before its commercialization. Oxide semiconductors offer many advantages such as stability in a variety of electrolytes, a diverse range of bandgaps and their Earth-abundance in nature. In this respect, many binary metal oxides have been investigated thoroughly; however, unfortunately, a suitable candidate for PEC water splitting has not been identified. While many efforts are ongoing to overcome the limitations of binary metal oxides, it is also essential to expand the search to more complex oxide families such as ternary, quaternary as well as to their composites. Nevertheless, this warrants a time-efficient route of synthesis to study such a large number of possible combinations (8,000 ternary and 700,000 quaternary oxides). Herein, we studied several complex oxides in the Cu-Bi-V-O system using a rapid- and energy-efficient solution combustion synthesis (SCS). We demonstrated the synthesis of binary CuO and α-Bi2O3 as well as their ternary combination, CuBi2O4. In addition, we prepared several composites of CuBi2O4 with binary CuO and α-Bi2O3. We systematically studied the optical and PEC behavior of these oxides and found improved photoactivities by the composites than their parent oxides which are attributed to the vectorial transfer of photogenerated carriers in them. Similarly, we developed a complexation-assisted solution combustion synthesis for multiple ternary copper vanadates. Four copper vanadates, namely α-CuV2O6, α/β-Cu2V2O7 and γ-Cu3V2O8, were prepared in “one-pot” by simply tuning the Cu/V mole ratio in the precursor solutions. This enabled comparative PEC performance assessment of these vanadates toward water splitting. The α-CuV2O6 polymorph outperformed the other three copper vanadates in PEC water splitting. This performance enhancement was attributed to its unique crystal structure and direct nature of the optical transition from the valence to the conduction band.

Keywords

Solar energy, Photoelectrochemical, Water splitting, Oxide semiconductors

Disciplines

Chemistry | Physical Sciences and Mathematics

Comments

Degree granted by The University of Texas at Arlington

Included in

Chemistry Commons

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