Molecular dynamics study on the thermodynamic stability and structural evolution of crown-jewel structured PdCu nanoalloys

Abstract

The novel crown-jewel (CJ) structured PdCu nanoalloys have attracted considerable interest in high-performance single-atom catalysis. The characteristics of demanding high-temperature calcination in the synthesis of these samples disable us from experimentally understanding the details of the thermal evolution behavior of PdCu nanoclusters during the heating process. In this work, by analyses of potential energy surface, bond order parameter, and radial distribution function, we have theoretically studied the thermodynamic stabilities and structural evolution of Pd-decorated Cu-based CJ nanoclusters with various compositions and sizes by molecular dynamics simulations. PdCu nanoclusters undergo a cuboctahedral (Cubo) to icosahedral (Ico) structural transformation before melting. This transformation is size- and Pd-composition dependent. The small size and high Pd-composition of PdCu nanoclusters facilitate this transformation. In addition, we find that the surface and interface effects of clusters have an important impact on the structural transformation and Cubo–Ico structural transformation is strongly related to the release of excess energy.