Au@void@AgAu Yolk-Shell Nanoparticles with Dominant Strain Effects: A Molecular Dynamics Simulation

Area of Science:

• Materials Science
• Nanotechnology
• Computational Chemistry

Background:

• Yolk-shell nanoparticles offer unique properties for various applications.
• Understanding the stability of bimetallic nanostructures is crucial for their practical use.
• Previous studies have explored nanoparticle stability, but the specific behavior of Au@void@AgAu structures requires further investigation.

Purpose of the Study:

• To investigate the structural stability of Au@void@AgAu yolk-shell nanoparticles with varying morphologies.
• To elucidate the factors governing the thermodynamic stability of these nanostructures.
• To compare simulation findings with experimental data for validation.

Main Methods:

• Classical molecular dynamics simulations were employed to model Au@void@AgAu nanoclusters.
• Simulations were conducted at room temperature to observe structural evolution.
• Thermodynamic stability was assessed by analyzing the competition between strain and surface energy effects.

Main Results:

• All simulated yolk-shell nanoclusters (approximately 3.8 nm) were found to be unstable at room temperature.
• Shell atoms collapsed into the void, forming more stable Au@AgAu core-shell structures.
• The thermodynamic stability of the resulting core-shell structures was morphology-dependent, with icosahedral structures showing the highest stability due to minimal strain.
• Strain energy effects were found to be dominant over surface energy effects in determining stability.

Conclusions:

• Au@void@AgAu yolk-shell nanoparticles of approximately 3.8 nm are unstable and spontaneously transform into core-shell structures.
• Nanoparticle size is the critical factor controlling stability, outweighing morphological influences.
• The icosahedral morphology exhibits superior thermodynamic stability in the resulting core-shell structures due to reduced strain energy.