Chemical Engineering Seminar
Renewable sources, such as wind and sun, supply more than enough energy to meet the increasing global demand and are promising solutions to shift our dependence away from fossil fuels as long as challenges with intermittency, scale, and cost effectiveness can be overcome. While recent developments have improved capture efficiencies for these sources, effective processes to convert and store this energy are needed. Chemical storage of energy using optimized catalytic reactions can produce high energy density fuels and commodity chemicals while allowing for spatiotemporal decoupling of the energy production and consumption processes. This talk will cover my recent work pursuing fundamental understanding of such catalytic reactions towards production of renewable fuels and chemicals. In addition, I will present a model for assessing practical efficiency limits for solar hydrogen production devices, as well as a water splitting device that achieves a record 30% solar-to- hydrogen efficiency.
Water oxidation, also known as the oxygen evolution reaction (OER), plays a key role in electrochemical processes such as water splitting and carbon dioxide reduction by providing the necessary protons and electrons to drive these reactions. Improving the efficiency and stability of OER catalysts can have a direct impact on device efficiency and cost effectiveness of renewable energy technologies. In this talk, I will discuss studies of controlled catalyst surfaces with an emphasis on determining intrinsic catalyst activity coupled with insights from advanced characterization techniques, such as x-ray absorption and x-ray emission spectroscopy, which are invaluable for investigating electronic, chemical, and geometric structure of materials. For example, using in situ x-ray absorption spectroscopy, changes in electronic structure for both manganese oxide and gold were investigated to understand why the combined catalyst material has an order of magnitude better activity than either catalyst alone. Furthermore, in collaboration with theory and by taking advantage of high-quality material growth techniques, a novel catalyst was developed that is stable in acid and outperforms known iridium oxide and ruthenium oxide systems, the only other OER catalysts that have reasonable activity in acidic electrolyte. Research at the interface of catalysis and spectroscopy towards developing a deeper understanding of these catalytic systems provides direction for further tuning of catalysts to develop the next generation of materials for renewable energy technologies.