  Pt-based bimetallic nanoparticles have attracted significant attention as a
promising replacement for expensive Pt nanoparticles. In the systematic design
of bimetallic nanoparticles, it is important to understand their preferred
atomic structures. However, compared with unary systems, alloy nanoparticles
present more structural complexity with various compositional configurations,
such as mixed-alloy, core-shell, and multishell structures. In this paper, we
developed a unified empirical potential model for various Pt-based binary
alloys, such as Pd-Pt, Cu-Pt, Au-Pt, and Ag-Pt. Within this framework, we
performed a series of Monte Carlo (MC) simulations that quantify the
energetically favorable atomic arrangements of Pt-based alloy nanoparticles: an
intermetallic compound structure for the Pd-Pt alloy, an onion-like multi-shell
structure for the Cu-Pt alloy, and core-shell structures (Au@Pt and Ag@Pt) for
the Au-Pt and Ag-Pt alloys. The equilibrium nanoparticle structures for the
four alloy types were compared with each other, and the structural features can
be interpreted by the interplay of their material properties, such as the
surface energy and heat of formation.
