Physical Sciences and Mathematics Commons^™

Synthesis And Characterization Of Indole-Based Zinc Dipyrrin Photosensitizers, Jean-Pierre Sanza

Electronic Theses and Dissertations

Metal complexes of dipyrromethene (dipyrrins) used as sensitizers in photocatalysis offer a way to harness solar energy in chemical bonds to create new fuels. This offers the dual role of reducing fossil fuel dependence and atmospheric CO₂ levels. Traditionally, metal dipyrrin complexes are synthesized using substituted pyrroles, aldehydes, and transition metals. Indoles have a more expanded pi-electron system and their dipyrrin-type complex may exhibit visible light absorption, suggesting that they can act as photosensitizers for CO₂ reduction processes. A novel indoledipyrromethene was synthesized using unsubstituted indole and mesitaldehyde. The complex exhibits visible light absorption at 422 nm. Its …

Quantum Mechanical Studies Of Water Splitting Reaction With (Zno)3 Nanoclusters As Catalysts, Duwage C. Perera

Electronic Theses and Dissertations

With the current energy crisis, H₂ production through the water-splitting reaction has drawn attention recently. In this thesis, I studied the structural (geometry) and electronic properties (vertical detachment energy and electron affinity) of ZnO monomers and dimers using density functional theory. ZnO is a metal oxide with a 3.37 eV band gap and can be a commercially cheaper photocatalyst in hydrogen (H₂) production. The B3LYP/DGDZVP2 pair was selected after investigating different pairs of exchange functionals and basis sets to study the hydration, hydrolysis, and water-splitting reaction. The singlet-triplet energy gaps of small (ZnO)_n clusters (n=1-6) of …

Advancements Toward Sustainable Solar Fuel Production Utilizing Reductive Homogeneous Electro- And Photocatalysis, Hunter Pratt Shirley

Electronic Theses and Dissertations

Molecular CO2 and H+ reductive catalysts, whether they be electro- or photocatalytic, have been shown to be possible routes of harnessing solar energy in a clean, renewable manner. There are few electrocatalysts operating at reasonable overpotentials to prove useful in artificial photosynthetic systems, and there are a number of environmental factors within these systems that have yet to be evaluated. Photo-driven catalysis is rare, difficult to control, and rarely provides high-value CO2 reduction products. I report herein an exceptionally low overpotential H+ reduction catalyst, a method of modulating electrocatalysts in-situ to improve performance, a first-of-its-kind mononuclear proton reduction photocatalyst, a …

(Pseudo)Phase Tuning In The Service Of Synthesis: Technologies For Sustainable Catalysis., Justin Douglas Smith

Electronic Theses and Dissertations

Strategies for manipulation of chemical phases were explored with emphasis on synthetic chemistry applications. Some strategies are fairly divergent from their origin, but all ultimately began from investigations of micellar media. Accordingly, Chapter 1 reviews the historical development of micellar catalytic processes. Chapters 2 and 3 detail development of synthetic methods in micellar solutions of designer surfactant PS-750-M. PS-750-M was designed to create benign micellar solutions which effectively mimic toxic organic solvents; it contains a proline-based linker between its hydrophobic and hydrophilic regions which imparts increased polarity to the micellar core. Chapter 2 details an interfacial nucleophilic substitution of perfluoroarenes …

Photocatalytic Carbon Dioxide Reduction With Zinc(Ii) Dipyrrin Photosensitizers And Iron Catalyst, Senan Rasheed

Electronic Theses and Dissertations

Much of the energy used in the United States and around the globe is obtained from petroleum, natural gas, and coal. Photocatalytic CO₂ reduction can be used to transform CO₂ to useful fuels and making fossil fuels more renewable. Input of energy is required, and the sun can provide the required energy for this transformation. Photosensitizer, catalyst, and electron donor are required for photocatalytic CO₂ reduction.

Due to lack of earth-abundant sensitizers, zinc dipyrrin complexes were synthesized by previous group members and have been used as photosensitizers in this research. The ground and excited state electrochemical properties …

Development Of Bismuth Oxyhalide Photocatalysts For Environmental And Industrial Applications, Robert Arthur

Electronic Theses and Dissertations

Heterogeneous semiconductor photocatalysis, of interest for water splitting and environmental remediation applications, uses light to drive reactions. Metal oxide and sulfide semiconductors have been previously studied but have limitations that include large band gap energies and high rates of recombination. Bismuth oxyhalides (BiOX) are an emerging class of photocatalysts with tunable band gaps and low rates of recombination due to their unique crystal structures. Studies of BiOX photocatalytic activity have largely focused on removal of azo dyes from aqueous solutions, with little attention paid to degradation byproducts. Furthermore, these catalysts have not been explored as a means to conduct organic …

Synthesis Of Fluorene-Based Derivatives, Characterization Of Optical Properties And Their Applications In Two-Photon Fluorescence Imaging And Photocatalysis, Grace Githaiga

Electronic Theses and Dissertations

The two-photon absorption (2PA) phenomenon has attracted attention from various fields ranging from chemistry and biology to optics and engineering. Two of the common NLO applications in which organic materials have been used are three-dimensional (3D) fluorescence imaging and optical power limiting. Two-photon absorbing materials are, therefore, in great demand to meet the needs of emerging technologies. Organic molecules show great promise to meet this need as they can be customized through molecular engineering, and as the development of two-photon materials that suit practical application intensifies, so does research to meet this need. However, there remains some uncertainty in the …

Efficient Utilization Of Solar Energy In Dye-Sensitized Solar Cells And In The Photocatalytic Reduction Of Carbon Dioxide, Aron Joel Huckaba

Electronic Theses and Dissertations

One of the most important questions humanity will face in the next 100 years is going to be "What will happen when oil runs out?" This dissertation describes efforts to utilize solar energy to improve renewable energy technology in two ways: First, through the improvement of dye sensitized solar cells by theimprovement of D-π-A dye subunits, the development of practical sensitizers, and progress towards stable, tunable redox shuttles. A novel indolizine donor subunit was synthesized that was shown to be the strongest reported donor. Dyes made from this novel donor and devices using the Γ-/I 3- reached up to 5.4% …