In search of the smoothest nanoparticle surface: diffusion and mobility on Ag clusters

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Surface diffusion is essential for nanoparticle growth and achieving regular shapes.
• Edges between facets can hinder adatom diffusion, acting as rate-limiting steps.
• Edge sharpness is hypothesized to influence diffusion barriers differently.

Purpose of the Study:

• To investigate how nanoparticle geometry affects adatom surface diffusion.
• To identify key edge-crossing processes and their activation barriers.
• To understand the relationship between edge sharpness and diffusion barriers.

Main Methods:

• Molecular dynamics simulations were employed.
• Simulations focused on silver adatoms on various nanoparticle shapes (tetrahedron, octahedron, Mackay icosahedron, chiral icosahedron).
• Activation barriers for edge-crossing diffusion processes were estimated.

Main Results:

• Nanoparticle geometry significantly influences inter-facet adatom diffusion.
• Edge sharpness affects jump and exchange diffusion barriers in opposing ways.
• Tetrahedron (sharpest) and chiral icosahedron (most rounded) exhibited the smoothest surfaces for adatom diffusion.

Conclusions:

• The geometric shape of nanoparticles is a critical factor controlling adatom diffusion.
• Optimizing nanoparticle shape can lead to enhanced surface diffusion, beneficial for growth and defect control.
• Findings are applicable to other face-centered cubic (fcc) metals.