Solid–Liquid Coexistence in Trimetallic Heterostructured Nanoparticle Catalysts: Insights from Molecular Dynamics Simulations

The chemical and physical properties of multimetallic heterostructured nanoparticles can be finely tuned by changing the structure and composition of metallic domains. Heat treatment ineluctably affects the structure and elemental distribution in each domain inside the nanoparticles. Here, we investigated the structural evolution of trimetallic heterostructured nanoparticles composed of Ag, Au, Cu, Ni, or Co under continuous heating by using molecular dynamics simulations. Both energy and Lindemann criteria were used to detect surface premelting and overall melting of each domain. Meanwhile, the common neighbor analysis was employed to identify the local structures. The simulations reveal that the melting processes are heterogeneous and stepwise. Solid and liquid phases could coexist in different domains respectively within variable temperature regions, facilitating the proceeding of different chemical and physical reactions on the nanoparticles. The width of the temperature region for solid–liquid coexistence is heavily dependent on the difference in the melting points of domains and hence can be tuned by adjusting the composition in the heterogenous nanoparticles. These results significantly extend the fundamental understanding of thermally driven structural evolution of multimetallic heterostructured nanoparticles and provide important insights into design and preparation of metallic nanoparticles with multifunctional properties.