Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 10: Solid-liquid Interfaces I

O 10.11: Talk

Monday, March 31, 2014, 13:00–13:15, WIL A317

Insights on the Microscopic Mechanisms of Anisotropic Growth of Gold Nanorods from Molecular dynamics simulations — •Santosh Meena and Marialore Sulpizi — Condensed Matter Theory, Institute of Physics, Johannes Gutenberg University, Staudingerweg 7, 55128 Mainz, Germany

Gold nanorods are normally prepared using seed-mediated growth technique, which require gold seeds, ascorbic acid and aqueous cetyltrimethylammonium bromide (CTAB) solution of HAuCL4. Crystal twinning of seeds results into formation of pentatetrahedral nanorod structure with different facets[1]. Although possible mechanism have been proposed, the microscopic understanding of the anisotropic growth is still missing. We provide the first atomistic model of adsorption of CTAB on different surfaces, namely (111), (110) and (100) in growing electrolyte solution. We find that on all the investigated surfaces, the CTAB form a layer of distorted cylindrical micelles where channels among micelles would provide direct ions access to the surface. In particular, we show how AuCl2- ions, can freely diffuse from the bulk solution to the gold surface[2]. Furthermore, we investigate the effect of halide ions (X= Cl- , Br- and I-) on adsorption of CTAX on the (111) surface and we provide a rational for the influence of halide ions on anisotropy of gold nanoparticles.

[1] C. J. Murphy, T. K. Sau, A. M. Gole, C. J. Orendorff, J. Gao, L. Gou, S. E. Hunyadi, T. Li, J. Phys. Chem. B 2005, 109, 13857-13870

[2] S. K. Meena, M. Sulpizi, Langmuir 2013, DOI: 10.1021/la403843n