Melting mechanisms of Pt-based multimetallic spherical nanoparticles by molecular dynamics simulation

CY Cheng and YY Guo and YM Zou and AJ Ong and AIY Tok and SZ Li, RARE METALS, 42, 406-417 (2023).

DOI: 10.1007/s12598-022-02160-5

The melting mechanisms of Pt-based multimetallic nanoparticles (NPs) are important to help determine their optimal melting processes. To understand the melting and coalescence behaviors of heterogeneous NPs (Pd-Pt NPs) with various sizes and compositions, molecular dynamics (MD) simulation was employed. The MD results for larger Pd-Pt NPs with an effective diameter of 4.6-7.8 nm show that PtPd alloy can form at Pd/Pt interface before Pd NP melted completely, while for Pt-core/Pdshell NP and Pd-core/Pt-shell NP, PtPd alloy formed only after Pd portion melted completely. For smaller Pd-Pt NPs with an effective diameter of 2.5-4.0 nm, PdPt alloy is not formed until both Pd and Pt NPs melted completely. Besides, the coalescence process of Pd-Pt NPs depends on the melting temperature of Pt NP when Pt composition is higher than 20 at%. Furthermore, the melting mechanisms of Pd/Pt/Ir trimetallic NPs are investigated. A two-step melting process occurs in Pd-Pt-Ir NPs and Ir- core/Ptshell/Pd-shell NP, and the melting sequence of Pd- core/Ptshell/Tr-shell NP and Pt-core/Pd-shell/Ir-shell NP is different from Pd/Pt bimetallic NPs.

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