Concave Pd-M (M = Co, Ni, Cu, Rh, Ag, Ir, Pt, and Au) nanocubes explored by molecular dynamics simulations: A liquid-like expansion mechanism

Abstract

MD simulations were used in the present study to evaluate the effects of various metallic frames (M = Co, Ni, Cu, Rh, Ag, Ir, Pt and Au) on the concavity endurance of Pd-M core-frame concave nanocubes at 300–800 K temperature range. The studied nanoparticles demonstrated a liquid-like expansion mechanism with simultaneous decrease of some coordination numbers and increase of the others. Also, it was found that two parameters affect on stability of the concave structure: first is the cohesive/surface energies and the second is diffusive ability of the frame atoms, in such a way that moderate cohesive/surface energies and low diffusive ability of the frame atoms lead to the most stable structures. According to the simulation results, Cu, Ag, and Au frames provided the lowest stable concave structures, Co, Rh, and Ir frames make the concave structures with moderate stability, and finally Ni and Pt frames created the highest stability for concave structure. It was also concluded that the stability of the concave structures for Pd-M nanocubes increases with overall nanoparticle size and therefore the frame size. These findings are expected to be effective for the production of core-frame concave nanoparticles with high concave stability for promising application in catalysis and nanotechnology.