Surface chemistry and gas-surface interactions related to catalytic and photo-catalytic processes are of interest from both a fundamental and an applied point of view. Very little is understood regarding chemical reactions on solid surfaces but they are crucially important in many industrial processes. We are interested in the mechanisms and kinetics of reactions of gas-phase molecules with model catalyst surfaces, e.g., planar metal-oxide supports decorated with metal nano-clusters and single crystalline metal surfaces populated with metal-oxide nanoparticles. For example, we are interested in the relationship between reactivity and cluster size and the interaction of the support with the cluster. We also maintain an active program in the growth of nanostructured, high-surface-area thin films for catalytic and photocatalytic surface chemical transformations.

EXPERIMENTAL CAPABILITIES

Currently we have three molecular beam surface scattering apparatus in our laboratories. Each is specially configured for the experiments currently being conducted with the apparatus, but all three machines have the capability for generating multiple beams. Generally, we employ the following techniques and equipment: temperature programmed desorption, Auger electron spectroscopy, Fourier-Transform Infra-Red surface vibrational spectroscopy, low energy electron diffraction, metal evaporation, and time of flight beam characterization. We also have a relatively new apparatus under construction to study surface photochemistry with applications in solar energy harvesting.

Water Chamber	Gold Chamber	Thin Film Growth Chamber

CURRENT RESEARCH PROJECTS

• R. A. Ojifinni, N. S. Froemming, J. Gong, T. S. Kim, M. Pan, T. S. Kim, J. M. White, G. Henkelman, and C. B. Mullins, “Water-enhanced low-temperature CO oxidation and isotope effects on atomic oxygen covered Au(111),” J. Am. Chem. Soc. 130, 6801-6812 (2008).  (PDF)
• J. Gong, R. A. Ojifinni, T. S. Kim, J. D. Stiehl, S. M. McClure, J. M. White, and C. B. Mullins, “Low temperature CO oxidation on Au(111) and the role of adsorbed water,” Topics in Catalysis 44, 57-63 (2007).  (PDF)
• Jinlong Gong, Rotimi A. Ojifinni, Tae S. Kim, J. M. White, and C. B. Mullins, “Selective catalytic oxidation of ammonia on atomic oxygen precovered Au(111),” J. Am. Chem. Soc. 128, 9012-9013 (2006).  (PDF)
• T. S. Kim, J. Gong, R. Ojifinni, J. M. White, and C. B. Mullins, “Water Activated by Atomic Oxygen on Au(111) to Oxidize CO at Low Temperatures” J. Am. Chem. Soc. 128, 6282-6283 (2006).  (PDF)

• J. D. Stiehl, J. Gong, R. A. Ojifinni, T. S. Kim, S. M. McClure, and C. B. Mullins, “Reactivity of Molecularly Chemisorbed Oxygen on a Au/TiO2 Model Catalyst,” J. Phys. Chem. B 110, 20337-20343 (2006).  (PDF)
• J. D. Stiehl, T. S. Kim, S. M. McClure, and C. B. Mullins, “Formation of Molecularly Chemisorbed Oxygen on TiO2-Supported Gold Nanoclusters and Au(111) from Exposure to an Oxygen Plasma Jet,” J. Phys. Chem. B 109, 6316-6322 (2005).(PDF)
• J. D. Stiehl, T. S. Kim, S. M. McClure, and C. B. Mullins, “Reaction of CO with molecularly chemisorbed oxygen on TiO₂-supported gold nanoclusters,” J. Am. Chem. Soc.  126, 13574-13575 (2004) (PDF)
• J. D. Stiehl, T. S. Kim, S. M. McClure, and C. B. Mullins, “Evidence for molecularly chemisorbed oxygen on TiO₂ supported gold nanoclusters and Au(111),” J. Am. Chem. Soc. 126, 1606-1607 (2004). (PDF)
• T. S. Kim, J. D. Stiehl, C. T. Reeves, R. J. Meyer, and C. B. Mullins, “Cryogenic CO oxidation on TiO₂ supported gold nanoclusters pre-covered with atomic oxygen,” J. Am. Chem. Soc. 125, 2018-2019 (2003). (PDF)

• D. W. Flaherty, Z. Dohnalek, A. Dohnalkova, B. W. Arey, D. E. McCready, N. Pnnusamy, C. B. Mullins, and B. D. Kay, “Reactive ballistic deposition of porous TiO2 films: growth and characterization,” J. Phys. Chem. C 111, 4765-4773 (2007). (PDF)

FUNDING SOURCES

Department of Energy - Basic Energy Sciences
National Science Foundation
Defense Threat Reduction Agency
Welch Foundation
American Chemical Society - Petroleum Research Foundation