Core(Fe)-shell(Au) nanoparticles obtained from thin Fe/Au bilayers employing surface segregation

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Core-shell nanoparticles offer unique properties for various applications.
• Developing cost-effective and scalable synthesis methods for these nanoparticles is crucial.
• Precious metal catalysts often rely on expensive materials like gold, platinum, and rhodium.

Purpose of the Study:

• To develop a novel method for synthesizing pure, single-crystalline iron-gold (Fe-Au) core-shell nanoparticles.
• To investigate the self-assembly mechanism driven by equilibrium segregation.
• To demonstrate the potential of these nanoparticles in nanotechnology and catalysis.

Main Methods:

• Fabrication of thin Fe/Au bilayer films on a sapphire substrate.
• Solid-state dewetting of the Fe/Au films at elevated temperatures.
• Characterization of nanoparticle morphology, crystallinity, and purity.
• Demonstration of nanoparticle detachment and surface modification.

Main Results:

• Successfully synthesized single-crystalline Fe-Au core-shell nanoparticles with high purity and thermal stability.
• Observed that gold (Au) atoms segregate to form a shell around iron (Fe) nanoparticles due to interfacial energy reduction.
• Demonstrated tunability of nanoparticle size by controlling initial film thickness.
• Showcased the ability to detach nanoparticles from the substrate and functionalize them with organic molecules.

Conclusions:

• The solid-state dewetting of Fe/Au bilayers is an effective method for producing Fe-Au core-shell nanoparticles.
• The equilibrium segregation phenomenon drives the formation of the core-shell structure.
• This scalable method can be extended to other metal combinations for catalysis, potentially reducing precious metal loading.