On the Relation between Spontaneous Segregation of Components in Ternary Pt–Pd–Ni Nanoparticles and Stability of Core–Shell Nanostructures: Molecular Dynamics Study

Abstract

The isothermal molecular dynamics method and the LAMMPS software package have been employed to perform a comparative study of the stability of Pd₅₀₀₀Ni₅₀₀₀@Pt₅₀₀₀, Pt₅₀₀₀Ni₅₀₀₀@Pd_5000, and Pt₅₀₀₀Pd₅₀₀₀@Ni₅₀₀₀ core-shell nanostructures during gradual heating from 300 to 2200 K. It has been revealed that all three homotopes retain their core–shell morphology up to the onset of melting. However, the ternary Pt₅₀₀₀Ni₅₀₀₀@Pd₅₀₀₀ nanoparticles have been found to be most stable: their melting begins at a higher temperature, and they partly inherit the core–shell morphology even after the completion of melting. A conclusion has been inferred about the relation between the higher stability of PtNi@Pd nanostructures and the effect of Pd surface segregation in ternary Pt–Pd–Ni nanoparticles. In turn, the pronounced surface segregation of Pd is explained by the fact that it is this component that has the lowest specific surface energy.