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CATEGORIES:Seminar,Webinar
DESCRIPTION:Surface science of shape-selective metal nanocrystal synthesis 
 from first-principles\n\nKristen A. Fichthorn\n\nDept. of Chemical Engineer
 ing\n\nPenn State University\n\nA significant challenge in the development 
 of functional nanomaterials is understanding the growth and transformations
  of colloidal metal nanocrystals.  Despite the tremendous strides made in n
 anocrystal synthesis science\, it is still difficult to achieve high\, sele
 ctive yields in most synthesis protocols.  Many aspects of these complex sy
 ntheses 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 scienc
 e are useful.\n\nI will discuss our efforts to understand the workings of P
 VP\, a polymer capping molecule that facilitates the formation of selective
  Ag nanoparticle shapes. In these studies\, we use first-principles density
 -functional theory (DFT) to characterize the interaction of PVP with Ag(100
 ) and Ag(111) surfaces.  To scale our calculations to the solution phase\, 
 we develop a metal-organic many-body force field with high fidelity to DFT.
   This allows us to predict kinetic shapes of large Ag nanocrystals (around
  100 nm) and show that these should be {100}-faceted cubes.  We also charac
 terize the interfacial free energies of PVP-covered Ag facets in solution a
 nd the Wulff shapes of Ag crystals\, which are truncated octahedra.  These 
 findings are consistent with experimental observations that sufficiently sm
 all Ag nanocrystals tend to have shapes with a predominance of {111} facets
  and larger nanocrystals become {100}-faceted during solution-phase growth 
 in the presence of PVP.\n\nAg nanowires can also be grown in ethylene glyco
 l solution with PVP.  Our calculations indicate that Ag nanowires with high
  aspect ratios\, comparable to experiment\, arise from surface diffusion.  
 On the other hand\, a synergistic interaction between adsorbed halide and c
 apping molecules leads to a higher flux of solution-phase cuprous ions to t
 he ends of Cu nanowires and promotes their growth.\n\nFor Webinar informati
 on please contact Kyle Page (kmp265@cornell.edu)
DTEND:20201008T210000Z
DTSTAMP:20260312T035505Z
DTSTART:20201008T200000Z
LOCATION:
SEQUENCE:0
SUMMARY:Materials Science and Engineering Seminar Series
UID:tag:localist.com\,2008:EventInstance_34713623146897
URL:https://events.cornell.edu/event/materials_science_and_engineering_semi
 nar_series_557
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