Hollow and Concave Nanoparticles via Preferential Oxidation of the Core in Colloidal Core/Shell Nanocrystals

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• 作者：Karol Miszta ; Rosaria Brescia ; Mirko Prato ; Giovanni Bertoni ; Sergio Marras ; Yi Xie ; Sandeep Ghosh ; Mee Rahn Kim ; Liberato Manna
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：June 25, 2014
• 年：2014
• 卷：136
• 期：25
• 页码：9061-9069
• 全文大小：586K
• ISSN：1520-5126

文摘

Hollow and concave nanocrystals find applications in many fields, and their fabrication can follow different possible mechanisms. We report a new route to these nanostructures that exploits the oxidation of Cu_2鈥?i>xSe/Cu_2鈥?i>xS core/shell nanocrystals with various etchants. Even though the Cu_2鈥?i>xSe core is encased in a thick Cu_2鈥?i>xS shell, the initial effect of oxidation is the creation of a void in the core. This is rationalized in terms of diffusion of Cu⁺ ions and electrons from the core to the shell (and from there to the solution). Differently from the classical Kirkendall effect, which entails an imbalance between in-diffusion and out-diffusion of two different species across an interface, the present mechanism can be considered as a limiting case of such effect and is triggered by the stronger tendency of Cu_2鈥?i>xSe over Cu_2鈥?i>xS toward oxidation and by fast Cu⁺ diffusion in copper chalcogenides. As the oxidation progresses, expansion of the inner void erodes the entire Cu_2鈥?i>xSe core, accompanied by etching and partial collapse of the shell, yielding Cu_2鈥?i>xS_ySe_1鈥?i>y concave particles.