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Chemistry, Physics and Astronomy, Ames Laboratory

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The outstanding catalytic activity and chemical selectivity of intermetallic compounds make them excellent candidates for heterogeneous catalysis. However, the kinetics of their formation at the nanoscale is poorly understood or characterized, and precise control of their size, shape as well as composition during synthesis remains challenging. Here, using well-defined Pt nanoparticles (5 nm and 14 nm) encapsulated in mesoporous silica, we study the transformation kinetics from monometallic Pt to intermetallic PtSn at different temperatures by a series of time-evolution X-ray diffraction studies. Observations indicate an initial transformation stage mediated by Pt surface-controlled intermixing kinetics, followed by a second stage with distinct transformation kinetics corresponding to a Ginstling-Brounstein (G-B) type bulk diffusion mode. Moreover, the activation barrier for both surface intermixing and diffusion stages are obtained through the development of appropriate kinetic models for analysis of experimental data. Our density-functional-theory (DFT) calculations provide further insights into the atomistic-level processes and associated energetics underlying surface-controlled intermixing.


This is a manuscript of an article published as Chen, Minda, Yong Han, Tian Wei Goh, Rong Sun, Raghu V. Maligal-Ganesh, Yuchen Pei, Chia-Kuang Frank Tsung, James Evans, and Wenyu Huang. "Kinetics, Energetics, and Size Dependence of the Transformation from Pt to Ordered PtSn Intermetallic Nanoparticles." Nanoscale (2019). DOI: 10.1039/C8NR10067E. Posted with permission.

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Creative Commons Attribution-Noncommercial 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 3.0 License

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The Royal Society of Chemistry



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