Ligand coverage dependence of structural stability and interparticle spacing of gold supracrystals

XP Liu and P Lu and H Zhai, JOURNAL OF APPLIED PHYSICS, 123, 045101 (2018).

DOI: 10.1063/1.5005094

Atomistic molecular dynamics simulations are performed to study the structural stability and interparticle spacing of alkylthiol-capped gold supracrystals with varying ligand coverage on gold nanocrystals. The results show that the gold supracrystal with dense ligand coverage is structurally stable, while a supracrystal with sparse ligand coverage is unstable due to the fusion of gold nanocrystals in the supracrystals. The ligand coverage dependence of the structural stability is attributed to the morphology of surface ligands on gold nanocrystals, which transforms from homogeneous to heterogeneous with decreasing ligand coverage. We show that the heterogeneous ligand distribution contributes to the fusion of gold nanocrystals and induces the structural instability of supracrystals. In addition, the interparticle spacing is found to increase linearly with increasing ligand coverage. The results may deepen our understanding of the origins of structural instability of gold supracrystals. Published by AIP Publishing.

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