Monodisperse SnO2-Coated Gold Nanoparticles Are Markedly More Stable than Analogous SiO2-Coated Gold Nanoparticles

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• 作者：Sang Ho Lee ; Irene Rusakova ; David M. Hoffman ; Allan J. Jacobson ; T. Randall Lee
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2013
• 出版时间：April 10, 2013
• 年：2013
• 卷：5
• 期：7
• 页码：2479-2484
• 全文大小：380K
• 年卷期：v.5,no.7(April 10, 2013)
• ISSN：1944-8252

文摘

This manuscript describes the synthesis of uniform monodisperse SnO₂-coated gold nanoparticles and examines their colloidal stability as function of pH, with direct comparison to better known and widely used SiO₂-coated gold nanoparticles. Aqueous acidic and basic colloidal SnO₂-coated and SiO₂-coated Au nanoparticle solutions were prepared, and their stability was monitored visually and by UV鈥搗is spectroscopy. Notably, the SnO₂-coated Au nanoparticle solutions were stable up to pH 12.5. However, at pH 13 and 14, the SnO₂-coated Au nanoparticles underwent aggregation, which could be fully reversed upon neutralization of the solutions. In contrast, the SiO₂-coated Au nanoparticle solutions were unstable at pH >10.5, irreversibly producing a precipitate composed of bare Au nanoparticle aggregates having little or no silica coating. Under acidic conditions, sedimentation was observed from both the colloidal SnO₂-coated and SiO₂-coated Au nanoparticle solutions, but the colloidal solutions could be reconstituted upon neutralization of the acidic solutions. The sedimentation at low pH coincided with the reported isoelectric pH values of SiO₂ and SnO₂, respectively. From an applications perspective, we are seeking to develop SnO₂-coated metal nanoparticles as stable alternatives to the more widely employed SiO₂-coated nanoparticles, with a particular emphasis on their use in sensor devices and solar cells.

Keywords:

SiO₂-coated nanoparticles; SnO₂-coated nanoparticles; colloidal stability; pH