Ostwald-Driven Phase Separation in Bimetallic Nanoparticle Assemblies

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• 作者：Geoffroy Prévot ; Nhat Tai Nguyen ; Damien Alloyeau ; Christian Ricolleau ; Jaysen Nelayah
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：April 26, 2016
• 年：2016
• 卷：10
• 期：4
• 页码：4127-4133
• 全文大小：541K
• 年卷期：0
• ISSN：1936-086X

文摘

The compositional stability of bimetallic nanoparticles (NPs) is crucial for many applications. We have studied the coarsening of amorphous carbon-supported Au–Pd NPs during annealing at 873 K. Using scanning transmission electron microscopy and energy-dispersive spectroscopy measurements, we show that, despite a complete miscibility of the two metals, the particle assembly undergoes a phase separation during annealing, which leads to two distinct populations: Au-rich NPs with a mean radius of 3.5 nm and large Pd-rich NPs with a mean radius of 25 nm. Thermodynamic calculations and kinetic Monte Carlo simulations explain this behavior that is driven by the competition between surface and mixing energy and by the different mobilities of the two atomic species.