Concerted Growth and Ordering of Cobalt Nanorod Arrays as Revealed by Tandem in Situ SAXS-XAS Studies

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• 作者：Benoit Cormary ; Tao Li ; Nikos Liakakos ; Laurent Peres ; Pier-Francesco Fazzini ; Thomas Blon ; Marc Respaud ; A. Jeremy Kropf ; Bruno Chaudret ; Jeffrey T. Miller ; Elizabeth A. Mader ; Katerina Soulantica
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：July 13, 2016
• 年：2016
• 卷：138
• 期：27
• 页码：8422-8431
• 全文大小：696K
• 年卷期：0
• ISSN：1520-5126

文摘

The molecular and ensemble dynamics for the growth of hierarchical supercrystals of cobalt nanorods have been studied by in situ tandem X-ray absorption spectroscopy–small-angle X-ray scattering (XAS-SAXS). The supercrystals were obtained by reducing a Co(II) precursor under H₂ in the presence of a long-chain amine and a long-chain carboxylic acid. Complementary time-dependent ex situ TEM studies were also performed. The experimental data provide critical insights into the nanorod growth mechanism and unequivocal evidence for a concerted growth–organization process. Nanorod formation involves cobalt nucleation, a fast atom-by-atom anisotropic growth, and a slower oriented attachment process that continues well after cobalt reduction is complete. Smectic-like ordering of the nanorods appears very early in the process, as soon as nanoparticle elongation appears, and nanorod growth takes place inside organized superlattices, which can be regarded as mesocrystals.