This journal is c The Royal Society of Chemistry 2013 Chem. Soc. Rev., 2013, 42, 2497--2511 2497 Cite this: Chem. Soc. Rev., 2013, 42, 2497 Controlled synthesis of colloidal silver nanoparticles in organic solutions: empirical rules for nucleation engineering† Yugang Sun* Controlled synthesis of colloidal nanoparticles in organic solutions is among the most intensely studied topics in nanoscience because of the intrinsic advantages in terms of high yield and high uniformity in comparison with aqueous synthesis. However, systematic studies on the formation mechanism of nanoparticles with precisely tailored physical parameters are barely reported. In this tutorial review, we take the synthesis of different Ag nanoparticles as an example to rule out the general principles for controlling the nucleation process involved in the formation of colloidal Ag nanoparticles in organic solutions, which enables the synthesis of high-quality nanoparticles. 1. Introduction Silver (Ag) is a ductile, malleable coinage metal that exhibits the highest electrical and thermal conductivity among all metals and high optical reflectivities, resulting in Ag being a widely used material in many areas such as electric contacts and conductors, mirrors, and catalysis of chemical reactions. As sizes of Ag particles decrease down to the nanometer scale, they exhibit many unique properties that cannot be observed in bulk Ag. For example, the high ductility of Ag dramatically reduced in Ag nanowires with fivefold twinning structures. 1 Synthesis of Ag nanoparticles boomed in the past decade and their corresponding properties and applications were extensively studied. 2–5 This progress has advanced the commercialization of manmade Ag nanomaterials that represent the most widely used materials in nanotechnology consumer products (i.e., 313 Ag-based products as analyzed on March 10, 2011). 6 For instance, Ag nanoparticles have been used as a class of broad-spectrum antimicrobial reagents in medical and consumer products such as household antiseptic sprays and antimicrobial coating for medical devices. 7,8 Water filters incorporating Ag nanowires have been demonstrated to be very efficient for cleaning water that is polluted with bacteria. 9 Due to the large surface-to-volume ratios of the Ag nanoparticles in comparison with their bulk counterparts, Ag nanoparticles have been used as classic catalysts for important industrial reactions including oxidation of ethylene to ethylene oxide, propylene to propylene oxide, and methanol to form- aldehyde. 10,11 Heterocyclizations, addition of nucleophiles to alkynes (or allenes, or olefins), cycloaddition reactions (e.g., enantioselective [2+3]-cycloaddition of azomethine and nitrilimine), [4+2]-cycloaddition of imines, and acetylenic C sp –H and C sp –Si bond transformations can also be achieved through Ag-catalyzed processes. 12,13 The high electrical and thermal conductivities of Ag make Ag nanoparticles to be widely used in electronics Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA. E-mail: ygsun@anl.gov † Part of the chemistry of functional nanomaterials themed issue. Yugang Sun Yugang Sun received his BS and PhD degrees in chemistry from the University of Science and Technology of China (USTC) in 1996 and 2001, respectively. He is currently a staff scientist for the Center for Nanoscale Materials at Argonne National Laboratory. He is the 2007 recipient of The Presidential Early Career Awards for Scientists and Engineers (PECASE) and the 2008 recipient of DOE’s Office of Science Early Career Scientist and Engineer Award. His current research interests focus on the synthesis of a wide range of nanostructures, including metal nanoparticles with tailored properties, the development of in situ synchrotron X-ray techniques for real-time probing of nanoparticle growth, and the application of these nanomaterials in energy storage, photocatalysis, and sensing. Received 28th July 2012 DOI: 10.1039/c2cs35289c www.rsc.org/csr Chem Soc Rev TUTORIAL REVIEW Published on 16 October 2012. Downloaded by Universidad Autonoma de Queretaro on 17/06/2015 19:10:32. View Article Online View Journal | View Issue