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Homogeneous Catalysis: Transition-Metal Based Reactions for Photoconversion and Remediation
E. Fujita and
C. Creutz The goals of our research are to gain fundamental understanding of processes involved in the chemical conversion of solar energy and to understand mechanisms of metal-mediated reactions for environmental remediation. The long-term storage of solar energy as fuels or valuable chemicals requires efficient coupling of light absorption, photo-induced electron transfer processes, and chemical transformations including bond-forming and cleavage reactions. We are focusing particularly on factors controlling the bond formation rates between photoproduced metal-based intermediates (such as reduced/oxidized catalysts with a vacant coordination site) and small molecules in the early stage of photoconversion processes. Mechanistic and kinetic knowledge is crucial to understanding photochemical activation of small molecules and to the design of more efficient photoconversion systems. Photogeneration of H2 and the photoreduction of CO2 have been our major focus in recent years. We are broadening our studies to include the photochemical activation of small molecules such as H2, CH2CH2, CH4, CO, other gaseous hydrocarbons, and N2 because of their relevance to our future energy needs, energy conservation, and environmental concerns. A new component of this effort explores the use of metal clusters nanoparticles as multiequivalent reducing agents. In principle, the clusters, stabilized by a layer of labile ligands, can be “charged” with more than one electron by a chemical, photochemical, or radiation chemical source and can bring about the reduction of protons or carbon dioxide bound at cluster surface sites. Oxidation of sulfur-containing and organic pollutant model systems by Fe(VI), (V), and (IV) will be probed in pulse-radiolysis experiments to determine reaction rates and mechanisms relevant to the utilization of ferrates in remediation.More info: Last Update on Friday April 23, 2004 |
