| Harvesting energy in environmentally responsible ways is one of the most important challenges facing human society. We envision a world where sunlight is harvested to produce chemical fuels, and where fuel cells provide electricity.
Fuels are stable in part, because their redox activity is confined to complex, multielectron pathways. As a result, catalysts are needed both to store energy in a fuel and to extract it. The goal of our research is to learn how to create and consume fuels more adeptly and efficiently, which is why we study multielectron redox catalysis.
The catalysts we study are transition metal complexes. Much of our effort is invested in designing and synthesizing macrocyclic or chelating ligands which tune the electronic environment at the metal and promote the desired redox activity. We are also interested in new ways of immobilizing
catalyst molecules on electrodes and other surfaces. Areas of current interest are listed below.
Electrocatalytic O2 Reduction. When hydrogen and oxygen are consumed in a fuel cell at ambient temperatures, much of the stored chemical energy is wasted. Conventional catalysts for the four-electron reduction of O2 to water are efficient only at high temperatures. We are investigating new catalysts for this reaction and new ways of confining them to electrodes.
Photochemical Water Splitting. Artificial photosynthesis of energy-rich
fuels is the "holy grail" of photochemical research. Simultaneous collection and storage of solar energy promises greater efficiency and lower cost than strategies where collection and storage are done sequentially. Photovoltaic cells using dye-sensitized, nanostructured TiO2 achieve outstanding efficiencies
in the conversion of solar energy to electricity. We are interested in applying a similar architecture to fuel-forming processes, such as water splitting.
Experimental techniques used in our laboratory include basic organic and inorganic synthesis, with characterization by IR,
UV-visible, and multinuclear NMR spectroscopies. To probe the all-important redox properties of our target systems, we employ a variety of electrochemical methods, including cyclic and hydrodynamic (rotating ring-disk) voltammetry and uv-visible spectroelectrochemistry.
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| "Preparation of Osmium Hydrazido Complexes by Interception of an Osmium(IV) Imido Intermediate," George M. Coia, Peter S. White, Thomas J. Meyer, David A. Wink, Larry K. Keefer and William M. Davis, J. Am. Chem. Soc.,
116, 3649 (1994).
"Trans-Cis Isomerization in [Os(tpy)(Cl)2(N)]+," Darryl S. Williams, George M. Coia and Thomas J. Meyer, Inorg. Chem., 34, 586 (1995).
"A Discussion of Electrochemical Techniques for the Detection of Nitric Oxide," David A. Wink, Danae Christodoulou, May Ho, Murali C. Krishna, John A. Cook, Harold Haut, J. Kemp Randolf, Melani Sullivan, George M. Coia, Royce Murray and Thomas J. Meyer, Methods, 7, 71, (1995).
"Osmium Hydrazido and Dinitrogen Complexes," George M. Coia, Martin Devenney, Peter S. White, Thomas J. Meyer and David A. Wink, Inorg. Chem., 36, 2341 (1997).
"OsIII(N2)OsII Complexes at the Localized-to-Delocalized, Mixed-Valence Transition," Konstantinos D. Demadis, El-Sayed El-Samanody, George M. Coia and Thomas J. Meyer, J. Am. Chem. Soc., 121, 535 (1999).
"Oxidation of Ammonia in Osmium Polypyridyl Complexes," George M. Coia, Konstantinos D. Demadis, and Thomas J. Meyer, Inorg. Chem., 39, 2212 (2000)
"Dye-Sensitization of Nanocrystalline Titanium Dioxide with Osmium and Ruthenium Polypyridyl Complexes," Genevieve Sauve, Marion E. Cass, George M. Coia, Stephen J. Doig, Iver Lauermann, Katherine E. Pomykal, and Nathan S. Lewis, J. Phys. Chem. B, 104, 6821 (2000)
"Current-Voltage Characteristics of Dye-Sensitized Nanostructured Semiconductor Photoelectrodes," George M. Coia and Nathan S. Lewis, submitted to J. Electrochem. Soc. "A Description of Nanostructured Semiconductor Membranes in Contact with Redox-Active Solutions," George M. Coia and Nathan S. Lewis, in preparation. |
