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Ligand-induced structural evolution of Pt55 nanoparticles: amine versus thiol
Ji Hoon Ryu1, Sang Soo Han, Da Hye Kim
1Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea.
ACS Nano
|October 4, 2011
Summary
Ligand choice influences platinum nanoparticle structure. Methylamine ligands promote transformation to icosahedral structures, while methylthiol ligands maintain cuboctahedral structures due to differing electronic effects.
Area of Science:
- Materials Science
- Computational Chemistry
- Nanotechnology
Background:
- Platinum nanoparticles (Pt NPs) exhibit diverse structural configurations.
- Understanding ligand-surface interactions is crucial for controlling NP properties.
- Bare Pt(55) nanoparticles favor icosahedral over cuboctahedral structures, but transformation is kinetically hindered.
Purpose of the Study:
- To investigate the geometric and electronic effects of amine and thiol ligands on Pt(55) NP structural transformations.
- To elucidate the mechanisms governing ligand-induced structural evolution in nanoparticles.
- To explore the potential for ligand-controlled NP structural engineering.
Main Methods:
- First-principles calculations were employed to model Pt(55) nanoparticle structures.
- The adsorption energies and geometric effects of methylamine and methylthiol ligands were analyzed.
- Activation barriers for structural transformations were computed.
Main Results:
- Methylamine adsorption facilitates the transformation from cuboctahedral to icosahedral structures via a Mackay transformation, driven by radial pulling and tangential contraction forces.
- Increased methylamine concentration can revert the icosahedral structure back to cuboctahedral due to orbital hybridization.
- Methylthiol adsorption results in weaker radial forces and tangential expansion, preventing structural transformation and stabilizing the cuboctahedral form.
Conclusions:
- The structure of Pt NPs can be effectively controlled by the type and amount of adsorbed ligands.
- Ligands with one lone pair (amine) promote structural transformation, while those with two lone pairs (thiol) stabilize the initial structure.
- This study highlights a pathway for designing and synthesizing nanoparticles with desired structural characteristics.
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