Silver‐Assisted Synthesis of Gold Nanorods: the Relation between Silver Additive and Iodide Impurities

Seed‐mediated methods employing cetyltrimethylammonium bromide (CTAB) as a surfactant, and silver salts as additives, are the most common synthetic strategies for high‐yield productions of quality Au nanorods. However, the mechanism of these reactions is not yet fully understood and, importantly, si...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2018-05, Vol.14 (20), p.e1703879-n/a
Main Authors: Jessl, Sarah, Tebbe, Moritz, Guerrini, Luca, Fery, Andreas, Alvarez‐Puebla, Ramon A., Pazos‐Perez, Nicolas
Format: Article
Language:English
Subjects:
Additives
Cetyltrimethylammonium bromide
Correlation analysis
Crystallography
CTAB
Gold
gold nanorods
Impurities
iodide and silver relation
Nanorods
Nanotechnology
Optimization
plasmons
Reagents
Reproducibility
seed‐mediated growth
Silver
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Summary:Seed‐mediated methods employing cetyltrimethylammonium bromide (CTAB) as a surfactant, and silver salts as additives, are the most common synthetic strategies for high‐yield productions of quality Au nanorods. However, the mechanism of these reactions is not yet fully understood and, importantly, significant lab‐to‐lab reproducibility issues still affect these protocols. In this study, the direct correlation between the hidden content of iodide impurities in CTAB reagents, which can drastically differ from different suppliers or batches, and the optimal concentration of silver required to maximize the nanorods yield is demonstrated. As a result, high‐quality nanorods are obtained at different iodide contents. These results are interpreted based on the different concentrations of CTAB and cetyltrimethylammonium iodide (CTAI) complexes with Ag+ and Au+ metal ions in the growth solution, and their different binding affinity and reduction potential on distinct crystallographic planes. Notably, the exhaustive conversion of CTAI–Au+ to CTAI–Ag+ appears to be the key condition for maximizing the nanorod yield. Here, the direct correlation between the (unpredictable) iodide content existing as an impurity in the cetyltrimethylammonium bromide reagent, and the silver amount required to maximize the fabrication of high‐quality Au nanorods in high yields is revealed.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.201703879