[ChBE-Grad] UH ChBE SABIC Seminar this Friday, April 22

[Solano, Nicolette]

[William A. Brookshire Department of Chemical and Biomolecular Engineering Seminar Series]<https://www.chee.uh.edu>

Surface Science of Shape-Selective Metal Nanocrystal Synthesis from First-Principles


Kristen A. Fichthorn
Professor
Pennsylvania State University

April 22 2022 | 10:30am Central
Room L2D2

Or virtually at https://urldefense.com/v3/__https://uh-edu-cougarnet.zoom.us/j/99200748343__;!!LkSTlj0I!H65xQWiDlSNcuxd6CnUjYE8Yt0xy-_-UPdTGOuQMyck-OC6iZWKsrlHLyJZYD14qsskFCw2qeuwU8djUcfgQiXNwm78$ 

LECTURE ABSTRACT
A significant challenge in the development of functional nanomaterials is understanding the growth and transformations of colloidal metal nanocrystals.  Despite the tremendous strides made in nanocrystal synthesis science, it is still difficult to achieve high, selective yields in most synthesis protocols.  Many aspects of these complex syntheses remain poorly understood and fundamental studies can be beneficial.  Since the shapes of metal nanocrystals are largely governed by phenomena occurring at their surfaces, studies based on principles in surface science are useful.

I will discuss our efforts to understand the growth of Cu and Ag nanocrystals through a multi-scale approach.  Using first-principles density-functional theory (DFT), we confirm experimental hypotheses that several commonly used capping molecules, such as PVP and various alkylamines, could facilitate nanoshape formation through their selective binding to particular crystal facets. To scale our calculations to the solution phase, we develop a metal-organic many-body force field with high fidelity to DFT.  Using the example of the PVP-mediated growth of Ag nanocubes, we employ molecular-dynamics simulations to predict both thermodynamic and kinetic Wulff shapes of Ag crystals.  These studies indicate that the relatively large (100 nm) cubic nanoshapes grown in experiments are kinetic in origin and can originate from differences in the Ag flux to different crystal facets.   Fivefold-twinned Ag nanowires can also be grown in solution with PVP.  Our calculations with absorbing Markov chains indicate that Ag nanowires with high aspect ratios, comparable to experiment, arise from surface diffusion.  On the other hand, a synergistic interaction between adsorbed chloride and capping molecules leads to a higher flux of solution-phase cuprous ions to the ends of Cu nanowires and promotes their growth.  We also find that surface diffusion can play a significant role in producing chlorine-covered Cu nanowires with high aspect ratios.





SPEAKER BIOSKETCH
Kristen Fichthorn is the Merrell Fenske Professor of Chemical Engineering and a Professor of Physics at the Pennsylvania State University. She received a B.S. in Chemical Engineering from the University of Pennsylvania and a Ph.D. in Chemical Engineering from the University of Michigan. She spent one year as an IBM Postdoctoral Fellow at the University of California at Santa Barbara before joining Penn State.
Professor Fichthorn's research is primarily in multi-scale materials simulation, in which she develops and applies theoretical techniques ranging from quantum density functional theory to molecular dynamics, Monte Carlo methods, and continuum theories to a diverse array of fundamental problems involving fluid-solid interfaces. Applications lie in nanoscale materials, thin-film and crystal growth, colloidal assembly, and wetting. In addition to being recognized by Penn State for her outstanding research and teaching, she is the recipient of the NSF Presidential Young Investigator Award (1990), an Alexander von Humboldt Research Fellowship (1998), she is a Fellow of the American Physical Society (2011), a Fellow of the American Institute of Chemical Engineers (2017), a recipient of the Nanoscale Science and Engineering Forum Award of the American Institute of Chemical Engineers (2019), and a recipient of the Langmuir Lectureship of the American Chemical Society (2020).





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[William A. Brookshire Department of Chemical and Biomolecular Engineering]<https://www.chee.uh.edu>

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