Thermal Stability of Platinum–Cobalt Bimetallic Nanoparticles: Chemically Disordered Alloys, Ordered Intermetallics, and Core–Shell Structures
2017
Huang, Rao | Shao, Gui-Fang | Zhang, Yang | Wen, Yu-Hua
Pt–Co bimetallic nanoparticles are promising candidates for Pt-based nanocatalysts and magnetic-storage materials. By using molecular dynamics simulations, we here present a detailed examination on the thermal stabilities of Pt–Co bimetallic nanoparticles with three configurations including chemically disordered alloy, ordered intermetallics, and core–shell structures. It has been revealed that ordered intermetallic nanoparticles possess better structural and thermal stability than disordered alloyed ones for both Pt₃Co and PtCo systems, and Pt₃Co–Pt core–shell nanoparticles exhibit the highest melting points and the best thermal stability among Pt–Co bimetallic nanoparticles, although their meltings all initiate at the surface and evolve inward with increasing temperatures. In contrast, Co–Pt core–shell nanoparticles display the worst thermal stability compared with the aforementioned nanoparticles. Furthermore, their melting initiates in the core and extends outward surface, showing a typical two-stage melting mode. The solid–solid phase transition is discovered in Co core before its melting. This work demonstrates the importance of composition distribution to tuning the properties of binary nanoparticles.
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