Insight into the Melting Behavior of Au–Pt Core–Shell Nanoparticles from Atomistic Simulations

Abstract

Comprehensive understanding of thermodynamic properties of metallic nanoparticles is of significance for their utility in catalysis. In this article, we have employed molecular dynamics simulations with quantum Sutton−Chen many-body potentials to examine the thermal stability of Au−Pt core−shell nanoparticles with different sizes during continuous heating. Our study shows that, for fixed particle size, the melting temperature is independent of core size for a small core while it is linearly decreased with a rising core radius for a large core. Diverse melting mechanisms have been discovered for different-core-sized nanoparticles. For a small core, the melting is progressively developed from the surface into the core, similar to that of monometallic nanoparticles. For a moderate or large core, an inhomogeneous melting has been found in these nanoparticles. The nucleation and activity of Shockley partial dislocations have initialized the local structural instability of the core−shell interface, leading to the inhomogeneous premelting of the Au core and the Pt shell for the moderate core. Nevertheless, when the core is large enough (resulting superthin shell), the diffusion of Au atoms from the core into the shell plays a dominant role in the destruction of the core−shell interface. This study provides a fundamental perspective on the melting behaviors of bimetallic (even multimetallic) nanoparticles at the atomistic level.

Tunable mechanical and thermal properties of ZnS/CdS core/shell nanowires

“…However, coating of a shell on top of the nanowire may affect the melting temperature of the core/shell nanowire, another important parameter which needs attention. Recently Sun et al investigated the melting behavior of metallic core/shell and alloyed nanoparticles extensively [41,[43][44][45][46]. They found that the melting behavior of core/shell nanoparticles significantly differs from that of its constituent materials.…”

“…In recent years, many experimental investigations have been carried out to synthesize and characterize different kinds of core/shell structures such as ZnO/ZnS [13], ZnO/CdS, [14] GaN/GaP, ZnO/TiO2 [15,16], CdSe/CdS [17,18], PbSe/CdSe [19,20], ZnS/CdS [21][22][23][24][25], CdS/ZnS [21,26,27], Ge/Si [28]. Both the classical molecular dynamics (MD) and density functional theory (DFT) methods have been used extensively to study the electronic [29][30][31][32][33][34][35], optical [29,36] and thermal [37][38][39][40][41][42][43][44][45][46][47][48] properties of the core/shell nanostructures. In contrast, mechanical properties of the core/shell nanostructures have so far not been investigated in details.…”

Electrochemically Induced Surface Metal Migration in Well-Defined Core–Shell Nanoparticles and Its General Influence on Electrocatalytic Reactions

“…42 In the hydrogen adsorption/desorption region (À0. 19 It can be seen in Figure 2a,b that with increased cycling a new peak grows in at 0.5 V on the cathodic scan. This peak corresponds to the reduction of oxidized Pd on a {100} facet and grows in next to the peak at 0.35 V corresponding to the reduction of oxidized Pd on a {111} facet.…”

“…Computational studies modeled the high-temperature melting of AuÀPt coreÀshell NPs, finding the migration of Au from core to shell to be inhomogeneous and dependent on shell thickness. 19 A recent experimental study used various calcination temperatures and gas environments to migrate Au in AuÀPt coreÀshell NPs and manipulate the ratio of Pt to Au in the alloyed shell, finding that the migration of Au from core to shell increased catalytic activity in electro-oxidations. They attributed this result to electronic and synergetic effects: the Au in the shell both altered Pt's electronic structure and manipulated the types of active sites available.…”

Structural studies of Au–Pd bimetallic nanoparticles by a genetic algorithm method

“…The Q-SC potential function provided an accurate description of inter-atomic interactions of monometallic clusters and obtained reasonable predictions of the thermodynamic and structural properties [23][24][25][26][27]. In addition, the Q-SC potential was widely used in atomistic simulation studies of alloy clusters, and shown good agreement with the results of experiment and theory [28][29][30][31][32].…”