Understanding the Mechanism of Mn-Promoted H2O Oxidation

University Of Washington, Seattle WA

Investigators

Abstract

With support from the Chemical Catalysis Program of the Chemistry Division of the National Science Foundation, Dr. Julie Kovacs of the University of Washington is studying new manganese compounds and their interactions with calcium and water. The long-range goal is to discover pathways for producing oxygen gas from water. This conversion is expected to be useful in the design of fuel cells. The approach is inspired by the roles of manganese catalysts in nature, which are known to form oxygen gas from water. This reaction is very simple on paper, but Nature's mechanism has not yet been demonstrated. The research examines how the structure of manganese catalysts influences their interaction with calcium ions, which in turn influences the reactions with water. In addition to this research, the grant is supporting work by Dr. Kovacs and a group of graduate students who provide instruction to K-12 students with the goal of enhancing their scientific literacy. As the Chair of the American Chemical Society’s Division of Inorganic Chemistry, she guides strategic planning with the goal of enhancing the leadership skills of younger chemists. Collectively, these activities strengthen the nation's scientific workforce by increasing its technical skills and diversity. With support from the Chemical Catalysis Program of the Chemistry Division of the National Science Foundation, Dr. Julie Kovacs of the University of Washington seeks to develop clean energy alternatives to fossil fuels. Her research, which is inspired by Nature’s photosynthetic water oxidation catalyst (OEC), requires an understanding of the key oxygen forming step. Very little is known about this step because it occurs following the rate-determining step. Sluggish water-oxidation catalysts limit existing fuel cells. Fundamental scientific research is therefore needed. The OEC catalyst stores oxidizing equivalents in preparation for the formation of dioxygen gas. She is using redox active ligands for this purpose. The redox inactive calcium ion is essential, and yet its role is still not understood. A calcium hydroxide has been proposed to attack an electrophilic manganese oxide. Kovacs’ group is testing this hypothesis using synthetic manganese-calcium, manganese-strontium, and manganese-manganese compounds. Molecules are designed to rapidly trap key intermediates. Transient absorption spectroscopy and magnetic resononace experiments as as well as computations complement the synthesis. In addition to her research, Dr. Kovacs leads a group of graduate students who provide instruction to K-12 students at the Seattle Public Library. As the Chair of the American Chemical Society’s Division of Inorganic Chemistry, she guides strategic planning with the goal of enhancing the leadership skills of female chemists. Collectively, these activities strengthen the nation's scientific workforce by increasing its diversity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.