Dr. Jill Millstone (Inorganic/Physical Seminar)
Title: "Superseding structural limitations in multimetallic nanoparticle synthesis"
Hosted By: Dr. Aaron Rossini & Dr. Javier Vela
Jill E. Millstone, Ph. D., Professor, Leo B. and Teresa Y. Wegemer Endowed Chair
Dept of Chemistry, University of Pittsburgh
Abstract: The formation of nanoparticles continues to challenge our understanding of what it means to make and form solid materials. Traditional theories describe colloidal nanoparticle formation as a nucleation process, with many works adding nuance to classic nucleation theory and related models. However, our conception of nanoparticle formation influences the synthetic techniques we apply and therefore the synthetic outcomes we obtain. In this work, we seek to establish, clarify, and in some cases challenge, theories about relationships between multimetallic nanoparticle formation trajectories and their resulting structures, including their stoichiometry, chemical ordering, crystallinity, and size. Our approach involves the development of exogeneous methods for controlling reaction kinetics including the use of photocatalytic reduction, which allows titration of reducing electrons into the reaction milieu with exceptional stoichiometric and temporal control. Our results indicate a remarkable dominance of kinetic factors such as reagent collision frequency, metal ion reduction kinetics, and neutral metal atom reaction trajectories in determining final nanoparticle morphologies, outcompeting the influence of thermodynamic factors such as metal bond dissociation energies and surface energies. Taken together, these new synthetic approaches yield not only critical insights into the fundamental chemical steps leading to multimetallic nanoparticle formation, but also translate that understanding into unprecedented and simultaneous control of particle stoichiometry and chemical ordering for multiple, bimetallic compositions.
Bio: Jill E. Millstone is a Professor and the Leo B. and Theresa Y. Wegemer Endowed Chair of Chemistry at the University of Pittsburgh with affiliated appointments in the Departments of Chemical Engineering and Mechanical Engineering and Materials Science. Since joining the faculty at Pitt in 2011, she has received honors including the NSF CAREER Award, the ACS Unilever Award for Outstanding Young Investigator in Colloid and Surfactant Science, the Cottrell Research Scholar Award, and the Kavli Emerging Leader in Chemistry Lectureship. She currently serves as an associate editor at ACS Nano, and on the editorial advisory board of several journals including Journal of Physical Chemistry Letters. She has served as the Chair of the Nanoscience Division within the Inorganic Chemistry Division of the American Chemical Society and as a Councilor from the Division of Colloid and Surface Chemistry. Her group studies the chemical mechanisms underpinning metal and metal-like nanoparticle formation, surface chemistry, and optoelectronic behaviors.