Pt-Co nanocluster in hollow carbon nanospheres.

Recently, it has been reported that small Pt/Co bimetallic nanoclusters into hollow carbon spheres (HCS) show outstanding catalytic performances in deriving biomass fuels due to the small particle size and the homogeneous alloying. Thus, the knowledge about the thermal evolution and stability of the nanoclusters into the HCS has a great importance. We have simulated the heating process beyond the melting point for the bare and encapsulated Pt/Co clusters into the HCS with the different sizes of 55, 147, and 309. The different thermodynamic and structural properties of the nanoclusters have also been investigated in this work. Our results show that the nanoclusters are more stable into the HCS than the bare clusters. The melting points of the supported clusters are also higher than the unsupported clusters. The confined nanoclusters have also lower excess energy values than the bare clusters which means that the encapsulation of Pt/Co nanoclusters into the HCS is favorable. The structural investigations show that a core-shell structure cannot be observed for the different supported and unsupported clusters and the initial mixed structure of the different nanoclusters remains also at the melting points. To more investigate this claim, the radial chemical distribution function (RCDF) and radial distribution function (RDF) of the bare and encapsulated clusters have also been calculated and discussed. © 2018 Wiley Periodicals, Inc.