International Research Fellowship Program: Photocatalytic Water Oxidation by Photosensitization of Nocera's Cobalt Phosphate Catalyst with Modified Ru\(II)\(bpy\) 3 Dyes

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0853127TilleyThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Stanley David Tilley to work with Dr. Michael Graetzel at the Ecole Polytechnique Federale de Lausanne in Switzerland.The proposed research project focuses on the oxidation half of the water splitting reaction (2H2O ?¨ 2H2 + O2) in which electrons are removed from water and an oxygen-oxygen bond is forged. In the reduction half reaction, these electrons are used to reduce protons to hydrogen. Using energy from the sun to drive the process allows for the storage of sunlight in the form of chemical bonds for use as fuels. The mastery of the photosensitized water oxidation reaction is critical to the long-term goal of generating hydrogen fuel from water using sunlight as the energy input.The recently discovered Nocera catalyst, which is based on the abundant and readily available transition metal cobalt, is capable of splitting water at neutral pH with an applied potential of 1.29V to generate oxygen. The proposed research seeks to eliminate the need for an applied voltage by anchoring a photosensitizing dye to the cobalt catalyst. The inorganic dye Ru(bpy)32+ was chosen as the photosensitizer as the Ru3+ form has been successfully used as a chemical oxidant for water oxidation. An appropriately functionalized Ru(bpy)32+ dye derivative will adsorb to the catalyst surface and function as a photosensitizer. It is expected that tethering an electron acceptor to the dye will improve charge separation and efficiency of electron extraction from the water oxidation catalyst. The electrons will then be captured by a soluble electron acceptor in solution. The long-term goal of this system is to pass the electrons into a hydrogen-generating system, although the current proposal is aimed only at laying the foundation of efficient photocatalyzed electron extraction from water and so uses a sacrificial electron acceptor.