CAREER: Theoretical Development of Bio-Inspired Water Splitting Photocatalysts

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Technical Abstract: This award by the Chemical Catalysis Program of the Chemistry Division supports the efforts of Professor Christine M. Aikens of Kansas State University to analyze which aspects of the oxygen-evolving center (OEC) of photosystem II contribute to its effectiveness as a catalyst for water splitting and therefore to predict which structural and electronic aspects are required in synthetic catalysts used for oxygen evolution. Professor Aikens employs a variety of electronic structure methods in order to accomplish this aim including: density functional theory, second-order perturbation theory, and multireference methods. Combined quantum mechanical/molecular mechanical (QM/MM) methods that include electrostatic embedding are employed to examine the role of the protein or solid-state support on catalytic activity. Some of the issues that are studied include the role of the protein backbone on structure and charge distribution in the Mn4Ca core, the impact of transition state energies on predicted overpotentials, the proper theoretical methods required to accurately model the catalytic cycle, how metal oxide clusters, single crystal surfaces, and nanostructured supports change the charge distribution and efficiency of the Mn4Ca reaction center, and whether the stoichiometry of the OEC plays a role in its effectiveness as a catalyst.Molecular modeling software is incorporated into the Chemistry 1 laboratories at Kansas State University in order to help students learn how to visualize molecular geometries. An annual one-day Energy and Sustainability Workshop for middle-school students focuses on topics such as solar power, biological energy, and other technology related to renewable energy and materials. Students attend introductory seminars and engage in hands-on activities. This workshop seeks to include rural students from sparsely populated areas as a means of broadening participation in science.Non-technical Abstract:This award by the Chemical Catalysis Program of the Chemistry Division supports the efforts of Professor Christine M. Aikens of Kansas State University to study aspects of the oxygen-evolving center (OEC) of photosystem II, a complex, naturally-occurring protein which uses light to produce oxygen, electrons and hydrogen ions (protons) from water. Biological systems have evolved efficient catalysts for water splitting to form oxygen during photosynthesis, but natural systems do not normally evolve hydrogen. This theoretical and computational research analyzes aspects of the oxygen-evolving center of photosystem II that contribute to its effectiveness as a catalyst for water splitting. Similar aspects are then targeted in synthetic materials. This research aids in the development of clean and renewable sources of energy for the 21st century. Molecular modeling software is incorporated into the Chemistry 1 laboratories at Kansas State University in order to help students learn how to visualize molecular geometries. An annual one-day Energy and Sustainability Workshop for middle-school students focuses on topics such as solar power, biological energy, and other technology related to renewable energy and materials. Students attending the workshop engage in hands-on, introductory activities. This workshop seeks to include rural students from sparsely populated areas as a means of broadening participation in science.