Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 45: Nonaqueous Liquid/Solid Interfaces

O 45.6: Vortrag

Mittwoch, 18. März 2015, 12:45–13:00, HE 101

Influence of halide ions on the anisotropic growth of gold nanoparticles: Insight from molecular dynamics simulations — •Santosh Meena¹, Andreas Henkel², and Marialore Sulpizi¹ — ¹Institute of Physics, Johannes Gutenberg University Mainz, Germany — ²Physical Chemistry Department, Johannes Gutenberg University Mainz, Germany

Halides ions play a fundamental role in controlling the anisotropic growth of gold nanorods [1]. In particular while Br- is able to promote anisotropic growth in seed mediated synthesis, Cl- is known to induce a faster isotropic growth. We studied the adsorption mechanism of CTAB/CTAC surfactant mixtures at different concentration ratio, namely 1:0, 1:1 1:2 and 0:1 on different gold surfaces, namely the (110), (100) and (111). We use molecular dynamics simulations in order to provide a detailed description of the gold/surfactant/electrolyte solution in the growing solution [2]. we found that Br- is not only responsible for surface passivation, but also acts as the driving force for the CTAB micelle adsorption and stabilization on the gold surface. When Br- is partially replaced by Cl-, the surfactant layer become less and less dense. Finally when all the CTAB is replaced by CTAC no halides or micellar structure protect the gold surface and further gold reduction is possible uniformly on all the facets resulting a isotropic faster growth.

[1] S. E. Lohse, N. D. Burrows, L. Scarabelli,L. M. Liz-Marzan, C. J. Murphy, Chem. Mater. 2014, 26(1), 34 [2] S. K. Meena, M. Sulpizi, Langmuir 2013, 29(48), 14954