title: Thermal Stability of Platinum-Cobalt Bimetallic Nanoparticles: Chemically Disordered Alloys, Ordered Intermetallics, and Core-Shell Structures.
abstract: 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.
authors.forename: Rao
authors.initials: R
authors.lastname: Huang
authors.forename: Gui-Fang
authors.initials: GF
authors.lastname: Shao
authors.affiliation: Department of Applied Physics, Xi'an Jiaotong University , Xi'an 710049, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yu-Hua
authors.identifier: http://orcid.org/0000-0002-0578-7506
authors.initials: YH
authors.lastname: Wen
keywords: alloy; core−shell structure; metallic nanoparticle; molecular dynamics; thermal stability