Deshmukh Rupali, Niederberger Markus
Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland.
Chemistry. 2017 Jun 27;23(36):8542-8570. doi: 10.1002/chem.201605957. Epub 2017 May 26.
The synthesis of metal oxide nanoparticles in organic solvents, so-called nonaqueous (or nonhydrolytic) processes represent powerful alternatives to aqueous approaches and have become an independent research field. 10 Years ago, when we published our first review on organic reaction pathways in nonaqueous sol-gel approaches, the number of examples was relatively limited. Nowadays, it is almost impossible to provide an exhaustive overview. Here we review the development of the last few years, without neglecting pioneering examples, which help to follow the historical development. The importance of a profound understanding of mechanistic aspects of nanoparticle crystallization and formation mechanisms can't be overestimated, when it comes to the design of rational synthesis concepts under minimization of trial-and-error experiments. The main reason for the progress in mechanistic understanding lies in the availability of characterization tools that make it possible to monitor chemical reactions from the dissolution of the precursor to the nucleation and growth of the nanoparticles, by ex situ methods involving sampling after different reaction times, but more and more also by in situ studies. After a short introduction to experimental aspects of nonaqueous sol-gel routes to metal oxide nanoparticles, we provide an overview of the main and basic organic reaction pathways in these approaches. Afterwards, we summarize the main characterization methods to study formation mechanisms, and then we discuss in great depth the chemical formation mechanisms of many different types of metal oxide nanoparticles. The review concludes with a paragraph on selected crystallization mechanisms reported for nonaqueous systems and a few illustrative examples of nonaqueous sol-gel concepts applied to surface chemistry.
在有机溶剂中合成金属氧化物纳米颗粒，即所谓的非水（或非水解）过程，是水相方法的有力替代方案，并已成为一个独立的研究领域。10年前，当我们发表第一篇关于非水溶胶 - 凝胶方法中有机反应途径的综述时，实例数量相对有限。如今，几乎不可能提供详尽的概述。在这里，我们回顾过去几年的发展，同时不忽略有助于追溯历史发展的开创性实例。在设计合理的合成概念并尽量减少试错实验时，深入理解纳米颗粒结晶和形成机制的机理方面的重要性再怎么强调也不为过。机理理解取得进展的主要原因在于表征工具的可用性，这些工具使得通过非原位方法（包括在不同反应时间后取样），但越来越多地也通过原位研究，来监测从前驱体溶解到纳米颗粒成核和生长的化学反应成为可能。在简要介绍了制备金属氧化物纳米颗粒的非水溶胶 - 凝胶路线的实验方面之后，我们概述了这些方法中的主要和基本有机反应途径。之后，我们总结了研究形成机制的主要表征方法，然后深入讨论了许多不同类型金属氧化物纳米颗粒的化学形成机制。综述最后一段介绍了非水体系中报道的选定结晶机制，以及一些应用于表面化学的非水溶胶 - 凝胶概念的示例。
