Structures, Thermal Stability, and Chemical Activity of Crown-Jewel-Structured Pd–Pt Nanoalloys

Abstract

In this work, the equilibrium structures, thermal stability, and chemical activity of crown-jewel (CJ)-structured Pd–Pt nanoalloys with highly symmetric cuboctaheral (Cubo), decahedral (Dec), and icosahedral (Ico) structures are studied by using molecular simulation based on the Gupta empirical potential and density functional theory (DFT) calculations. It is found that both the melting temperature and stability of CJ-structured Pd–Pt nanoalloys with the same size follow the order of Ico > Dec > Cubo, which agrees with the rule that the more stable the cluster, the higher the melting point. In addition, the melting temperature of CJ-structured Pd–Pt nanoalloys with the same morphology is of the same linear behavior with the inverse diameter of the clusters, which is consistent with the Pawlow's law. The adsorption properties of O on these Pd–Pt nanoalloys are studied to model the chemical activity of these nanoalloys. For the CJ-structured Pd12Pt43, the adsorption strength of O follows the order of Dec < Cubo < Ico, and the adsorption strength per O atom decreases slightly with increasing coverage of the O atom. In addition, the adsorption strength of O on the CJ-structured Pd12Pt43 is stronger than that on the CJ-structured Pd12Pt135. Our results show that the structures, thermal stability, and chemical activity of CJ-structured Pd–Pt nanoalloys are size- and morphology-dependent, which would shed new light on the design of CJ-structured nanoalloys as catalysts.