No description available.

No description available.

Thesis (Ph. D.)--Florida State University, 2003. / Advisor: Dr. Adriana Moreo, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Apr. 9, 2004). Includes bibliographical references.

No description available.

Thesis (Ph.D.) -- McMaster University, 1997 / Includes bibliographical references Also available via World Wide Web.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Jack Crow, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Jan 18, 2005). Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: John E. Greedan. Also available via World Wide Web.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2005. / Includes bibliographical references.

In this dissertation, I present four projects on the fundamental study of the surface configurations and reactivity of the metal oxides using density functional theory computational method. In the first project, we studied the formaldehyde adsorption and diffusion on rutile TiO2 (110) surface. By comparing the adsorption of formaldehyde on stoichiometric and defective TiO2 surfaces under the same condition, we evaluated the effect of surface oxygen vacancy on their interaction with formaldehyde. The project involved close collaboration with Dr. Zhenrong Zhang’s group of Baylor University who studied the formaldehyde chemistry on rutile TiO2(110) surface using a combination of STM and other surface science techniques. In the second project, we compared the surface chemistries of formaldehyde and formic acid on rutile TiO2 and SnO2, two structurally similar but chemically different oxides. We analyzed the oxidation of formaldehyde to formic acid on two oxides and assessed the role of surface oxygen in the oxidation. In the third project, we studied the oxygen evolution reaction (OER) catalyzed by γ-FeOOH (010) under the alkaline condition. The OER process was divided into four elementary steps and the potential energy profiles of these steps on three terminations of the γ-FeOOH (010) surface were mapped out. Based on the computed reaction energies, we determined the most probable OER reaction pathway on each surface termination. We found that partially exposed surface Fe sites were the active sites for the OER process. In the fourth project, we studied the potential of iron oxides (FeOx) and iron-titanium mixed oxides (FeTiOx) as solid oxygen carriers for the chemical looping combustion (CLC) process. As oxygen carriers for CLC, FeOx and FeTiOx in fully oxidized forms went through a series of reduction steps by reacting with the fuel molecules. The reduced oxides were then re-oxidized in an air reactor to restore their oxygen. By studying the surface oxygen vacancy formation and oxygen diffusion, we gained insights into the initial stage of reduction process and activities of FeOx and FeTiOx as well as the effect of Ti on oxygen carrying properties of FeTiOx for CLC.

"Catalysts are involved at some stage in the manufacture process of virtually all commercially produced chemical product. Among the materials used as catalysts, metal oxides are one of the most used due to their versatility and wide range of physical properties. Identifying the principles of surface to adsorbate charge transfer is key to a better understanding of metal oxide materials as both catalysts and gas sensors. Using density functional theory (DFT), we modeled the adsorption of small molecules over stoichiometric and reduced metal oxide surfaces of group IV metals and quantify the effect of electron transfer upon adsorption. We found that charge transfer only occurs during the adsorption process of an adsorbate more electronegative than the surface. We also found a correlation between the work function of the metal oxide, and the ionic adsorption of the oxygen molecule. Mixed phase rutile/anatase catalysts show increased reactivity compared with the pure phases alone. However, the mechanism causing this effect is not fully understood. Using DFT and the +U correction we calculated the bands offsets between the phases taking into account the effect of the interface. We found rutile to have both higher conduction and valence band offsets than anatase, leading to an accumulation of electrons in the anatase phase accompanied by hole accumulation in the rutile phase. We also probed the electronic structure of our heterostructure and found a gap state caused by electrons localized in undercoordinated Ti atoms which were present within the interfacial region. Interfaces between bulk materials and between exposed surfaces both showed electron trapping at undercoordinated sites. Finally, we studied the effect of the size of gold nanoparticles in the catalytic properties of gold decorated titania surfaces. We found that the adsorption energy of several intermediates reactives in the CO oxidation and water gas shift reaction does not change with the size of the nanoparticles. In conclusion, the factor that affects the reactivity of the system is the density of undercoodinated gold atoms on the interface perimeter."