nn1c01500_si_002.pdf (4.77 MB)
Download fileGeneral Trends in Core–Shell Preferences for Bimetallic Nanoparticles
journal contribution
posted on 23.04.2021, 11:34 authored by Namsoon Eom, Maria E Messing, Jonas Johansson, Knut DeppertSurface segregation
phenomena dictate core–shell preference
of bimetallic nanoparticles and thus play a crucial role in the nanoparticle
synthesis and applications. Although it is generally agreed that surface
segregation depends on the constituent materials’ physical
properties, a comprehensive picture of the phenomena on the nanoscale
is not yet complete. Here we use a combination of molecular dynamics
(MD) and Monte Carlo (MC) simulations on 45 bimetallic combinations
to determine the general trend on the core–shell preference
and the effects of size and composition. From the extensive studies
over sizes and compositions, we find that the surface segregation
and degree of the core–shell tendency of the bimetallic combinations
depend on the sufficiency or scarcity of the surface-preferring material.
Principal component analysis (PCA) and linear discriminant analysis
(LDA) on the molecular dynamics simulations results reveal that cohesive
energy and Wigner–Seitz radius are the two primary factors
that have an “additive” effect on the segregation level
and core–shell preference in the bimetallic nanoparticles studied.
When the element with the higher cohesive energy also has the larger
Wigner–Seitz radius, its core preference decreases, and thus
this combination forms less segregated structures than what one would
expect from the cohesive energy difference alone. Highly segregated
structures (highly segregated core–shell or Janus-like) are
expected to form when both the relative cohesive energy difference
is greater than ∼20%, and the relative Wigner–Seitz
radius difference is greater than ∼4%. Practical guides for
predicting core–shell preference and degree of segregation
level are presented.