With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry, Dr. Kathryn Knowles of the University of Rochester will develop novel synthetic approaches to mixed-metal oxide nanocrystals and investigate their properties. This research aims to generate a comprehensive fundamental understanding of the structure-property relationship in this class of nanocrystals that has the potential to facilitate rapid degradation, using sunlight, of persistent organic pollutants in water sources. These pollutants, such as dyes, pesticides, herbicides, and "forever chemicals" (per- and polyfluoroalkyl compounds), in the environment can have negative impacts on human health. The magnetic properties of the nanocrystals will allow their easy recovery from solution after use. Dr. Knowles and her team also seek to cultivate positive attitudes about scientific research in undergraduate and elementary school students by engaging them in activities that capture the creative and collaborative aspects of scientific research. These activities include an open-ended, inquiry-based capstone project to be incorporated into an upper-level undergraduate physical chemistry course and scientific activities that will be disseminated to a large, diverse cohort of elementary school students in a virtual format during National Chemistry Week.
The long-term goal of this research is to enable the rational design of visible light-absorbing semiconductors with efficient separation of photogenerated charges and slow carrier recombination kinetics for used as photoactive components of light-harvesting technology. This research will integrate nanocrystal synthesis, electronic structure calculations, and spectroscopic measurements to generate a comprehensive fundamental understanding of the relationships between composition, electronic structure, photophysical properties, and excited state dynamics of colloidal spinel oxide nanocrystals of general formula AB2O4. The Knowles group will establish a library of heterobimetallic molecular cluster precursors that will provide access to a broad range of spinel oxide compositions. Incorporating main group and transition metal cations into the same metal oxide nanocrystals will enable systematic examination of the synergistic effects of combining metal cations containing empty s-orbitals and partially filled 3d orbitals on the optical, electronic, and excited state properties of metal oxide nanocrystals. Density functional theory calculations, transient absorption and electrochemical impedance spectroscopies, and photocatalysis experiments will (i) predict and confirm the dependence of electronic and photophysical properties of spinel oxide nanocrystals on their composition and (ii) correlate the band-edge redox potentials and excited-state dynamics of these nanocrystals with their ability to photocatalyze the oxidative degradation of a broad range of organic pollutants.
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.
