Side Reactions in Controlling the Quality, Yield, and Stability of High Quality Colloidal Nanocrystals

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• 作者：Yongfen Chen ; Myeongseob Kim ; Guoda Lian ; Mathew B. Johnson ; and Xiaogang Peng
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：September 28, 2005
• 年：2005
• 卷：127
• 期：38
• 页码：13331 - 13337
• 全文大小：484K
• 年卷期：v.127,no.38(September 28, 2005)
• ISSN：1520-5126

文摘

Effects of side reactions during the formation of high quality colloidal nanocrystals were studiedusing ZnO as a model system. In this case, an irreversible side reaction, formation of esters, was identifiedto accompany formation of ZnO nanocrystals through the chemical reaction between zinc stearate and anexcess amount of alcohols in hydrocarbon solvents at elevated temperatures. This irreversible side reactionmade the resulting nanocrystals stable and with nearly unity yield regardless of their size, shape, andsize/shape distribution. Ostwald ripening and intraparticle ripening were stopped due to the extremely lowsolubility/stability of the possible monomers because all free ligands in the solution were consumed by theside reaction. However, focusing on size distribution and 1D growth that are needed for the growth of highquality nanocrystals could still occur for high yield reactions. Upon the addition of a small amount of stearicacid or phosphonic acid, immediate partial dissolution of ZnO nanocrystals took place. Although the excessalcohol could not react with the resulting zinc phosphonic acid salt, it could force the newly formed zincstearate gradually but completely back onto the existing nanocrystals. The results in this report indicatethat side reactions are extremely important for the formation of high quality nanocrystals by affecting theirquality, yield, and stability under growth conditions. Due to their lack of information in the literature andobvious practical advantages, studies of side reactions accompanying formation of nanocrystals areimportant for both fundamental science related to crystallization and industrial production of high qualitynanocrystals.