Sustainable Chemistry through Catalysis
Research in our group is divided among three major goals, all tied together by the common theme of sustainability through catalysis. We synthesize our catalysts using standard organic and inorganic techniques, and characterize their activities through a variety of techniques, including electrochemistry, kinetic analysis via UV-Vis, NMR and MS. We also study their mechanisms through time resolved spectroscopy aided by DFT calculations. As members of the Center for Sustainable Materials Science (CSMS) we are particularly focused on reactions that improve the sustainability and efficiency of polymer precursor production.
Developing Catalytic Oxidation Reactions Using Oxygen Gas
Oxidation reactions are critical to numerous chemical transformations, and thus developing oxidation reactions that rely on renewable and environmentally friendly oxidants touches on all areas of chemistry. Fortunately nature has provided us with an abundant and eminently renewable chemical oxidant, the oxygen in the air we breathe. Oxygen is in many ways an ideal oxidant: the only byproduct of its reduction is water, it is non-toxic under most conditions, and the reduction potential it provides is more than sufficient to drive many chemical transformations. Despite these benefits, slow reaction kinetics and incompatibility with many organic solvents severely restrict the use of oxygen in industrial settings. One of the primary focuses of our group is developing catalysts to mediate selective oxidation reactions using oxygen as the sole oxidant.
Understanding the Mechanism of Small Molecule Activation
A problem related to the use of oxygen as a chemical oxidant is our understanding of small molecule activation. Natural systems make ready use of the small molecules abundantly available in the atmosphere, e.g. N2, O2, CO2, and H2O, to make chemicals of remarkable complexity. For this reason the biological mechanisms by which these small molecules are activated have been extensively researched, and our understanding of the natural systems has been greatly improved. Despite these advances, we are still not able to reliably design catalysts that can convert these abundant and simple molecules into more useful forms. The second focus of our group is studying catalysts known to activate these simple molecules in order to better understand their mechanisms. The insights gained from this study will allow us to develop improved catalysts for small molecule activation.
Designing Artificial Photosynthetic Cells
Our third aim is developing methods for combining the water oxidation and proton reduction reactions required for artificial photosynthesis into a single device. Solar energy is the most promising source of renewable energy; however its intermittency has prevented its wide scale deployment. In order to overcome this problem intense research efforts have been made toward developing devices capable of mimicking natural photosynthesis. These artificial photosynthetic cells store solar energy as a chemical fuel for later use. Remarkable progress has been made toward the design of catalysts for the two half reactions of artificial photosynthesis, proton reduction to hydrogen gas and water oxidation to oxygen gas. Designing a device that can drive both of these reactions simultaneously using sunlight as the energy source remains extremely challenging. The primary challenge in combining these reactions is unproductive charge recombination of the transient oxidizing and reducing equivalents (or light-driven charge-separated states) required to drive these two chemical reactions. Our group is investigating methods for preventing this recombination, and thus enabling high-efficiency artificial photosynthetic devices.