Rattle, Porous, and Dense Cores and Discontinuous Porous, Continuous Porous, and Dense Shells in Pt@Au Core–Shell Nanoparticles

Abstract

In this study, Pt@Au core–shell nanoparticles were simulated by a classical molecular dynamics method to investigate the influences of morphologies of the core and shell regions on structural stability and melting behavior of these nanoparticles. For this aim, the nanoclusters with the same shell and different cores including rattle-core, porous-core, and dense-core types were considered. Through investigation of the shell effect, nanoclusters with the same core and different shells including dense-shell, continuous porous-shell, and discontinuous porous-shell were selected. The data for simulations were analyzed by potential energy, heat capacity, excess energy, deformation parameter, common neighbor analysis, and radial distribution function methods. The results indicated that dense-core and dense-shell nanoclusters exhibit the highest thermodynamic stability and melting point. Among various core morphologies, porous-core, and among various shell structures, the discontinuous porous-shell structure showed the lowest thermodynamic stability. The results indicated that melting starts from the shell region, and there is a considerable tendency for Pt atoms in the core to mix with Au atoms in order to create a mixed alloy at higher temperatures. This result implies the instability of core/shell regime at high temperatures.

Boron Nitride- and Graphene-Supported Trimetallic Yolk–Shell and Hollow Nanoparticles

“…It is observed that the void space is unstable in all nanoparticles and is filled by the collapse of atoms. This result was observed in our previous studies on yolk–shell and hollow nanoparticles. − Our previous results indicated that the stability of yolk–shell nanoparticles is dependent on the ratio of external radius to the shell thickness ( r ext /shell–thickness). The large nanoparticles with the largest shell–thickness have the smallest r ext /shell–thickness ratio and consequently have the highest void stability .…”

“…Our results showed that dense-core and dense-shell NPs have the highest thermal stability. Also, results showed that porous-core and discontinuous porous-shell have the lowest thermal stability . In another work, our results showed that various structural factors such as geometries of the shell and core, core size, shell thickness, and shell composition are effective ways of increasing the thermal and structural stability of the YSNPs …”

“…Also, results showed that porous-core and discontinuous porous-shell have the lowest thermal stability. 58 In another work, our results showed that various structural factors such as geometries of the shell and core, core size, shell thickness, and shell composition are effective ways of increasing the thermal and structural stability of the YSNPs. 59 As demonstrated in above studies, there are many strategies to enhance the thermodynamic stability of YSNPs and HNPs, such as size, core and shell morphology, and shell thickness.…”

“…As demonstrated in above studies, there are many strategies to enhance the thermodynamic stability of YSNPs and HNPs, such as size, core and shell morphology, and shell thickness. − In addition, as mentioned before, experimental studies demonstrate that the supports such as graphene can have a strong impact on the stability and catalytic activity of YSNPs and HNPs. Despite this, there are no MD studies on the influence of supports on the stability of YSNPs and HNPs.…”

“…There are several studies on the structural stability and thermal behavior of YSNPs and HNPs by our group. − For example, in previous work, we studied the effects of core and shell sizes on the thermodynamic stability of Au@void@Ag YSNPs through MD simulations. Our results indicated that YSNPs are unstable at temperatures below 350 K and through collapse into the void space create a more stable core–shell configuration.…”