Events Calendar

Catalyst Discovery for Metal-Free, Photoredox CO2 Reduction

Speaker: Dr. Shaama Sharada, Assistant Professor

Talk Title: Catalyst Discovery for Metal-Free, Photoredox CO2 Reduction

Abstract: Organic photoredox catalysis will be an important part of an energy-efficient, sustainable future as these
catalysts can access highly reactive states upon excitation and quenching to carry out reactions that are
otherwise thermally inaccessible or energy-intensive. Our group aims to identify sustainable photoredox
routes for CO2 utilization. Prior experiments show that a simple organic chromophore, p-terphenyl, can
reduce and transform CO2 into useful molecules such as amino acids. However, the steps of the photoredox
cycle and reasons for low turnover numbers of these catalysts are poorly understood. Our goal is to utilize
quantum chemistry methods to delineate mechanisms of key steps in this cycle and leverage these insights to
drive discovery of novel chromophores that are both active and yield high turnover numbers. Thus far, we
have demonstrated that the electron transfer (ET) step from the p-terphenyl radical anion to CO2 is adiabatic,
and ET barriers are lowered when electron-donating groups are substituted to p- terminal positions of the
catalyst. To probe degradation pathways from the excited state, we are establishing a protocol for calculation
and characterization of excited-state donor-acceptor charge transfer complexes in collaboration with the
Dawlaty group (USC). We are also taking our first steps towards driving discovery of new chromophores by
implementing a genetic algorithm (GA) whose fitness function factors in both catalyst activity and
degradation resistance by means of simple descriptors obtained from routine DFT calculations. The GA yields
several candidates that are more viable than experimentally studied terphenyls, highlighting the importance of
automated computational tools in accelerating experimental efforts.

Biography: Dr. Shaama Mallikarjun Sharada is the WiSE Gabilan Assistant Professor in the Mork Family Department of
Chemical Engineering and Materials Science and Assistant Professor in the Department of Chemistry at USC.
Her research interests span the development and application of quantum chemistry methods to design catalysts
for sustainable chemistry transformations. Her group is developing efficient algorithms, inspired from signal
processing, for advancing sophisticated rate theories in catalysis. The group is also establishing frameworks for
catalyst design and discovery towards efficient natural gas conversion and light-assisted carbon dioxide
utilization. Dr. Sharada received her Bachelors and Masters in Chemical Engineering from the Indian Institute
of Technology, Bombay (India) where she was awarded the Institute Gold Medal. She received her PhD in
Chemical Engineering from UC Berkeley in 2015 for developing efficient reaction path search algorithms for
catalysis. As a postdoctoral researcher at Stanford University, her work spanned the development of machine
learning density functionals and surface chemistry benchmarking databases. She is a recipient of the 2022
inaugural Chevron Research Innovation Award (USC) and the 2020 ACS Petroleum Research Fund Doctoral New Investigator Award. She is also a Scialog Fellow for the Negative Emissions Science initiative.

Host: Mork Family Department

More Information: Shaama Sharada Seminar Flyer 9 20.pdf

Location: James H. Zumberge Hall Of Science (ZHS) - 352

Audiences: Everyone Is Invited

Contact: Anthony Tritto