Synthesis of metallic Janus nanoparticles using silica as a protecting group

by Crane, Cameron Cowgur; Chen, Jingyi

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Rational synthesis of heterogeneous and higher order nanoparticles faces the practical challenge of controlling nucleation and growth at specific sites using wet chem. techniques. We report a new solid-state method for synthesis of binary metal nanoparticles using silica as a protecting group to control the nucleation sites. In this approach, a dimmer structure of gold-silica has been prepd. by modifying the conventional oil-in-water microemulsion. The dimmer structure is much more preferable compared to conventional co-axial core-shell structure for our purpose, and can be achieved through control of the amt. of sillicate precursor. These silica-protected gold nanoparticles serve as seeds for subsequent asym. seeded growth of other components. Following this growth, the silica protecting group can be selectively etched resulting in Janus nanoparticles. Several noble metals are used to demonstrate the versatility of this synthetic approach. We will discuss the results, characterization, and applications of new Janus nanoparticles.