Nanocrystal Conversion Pathways for the Synthesis of Multimetallic Nanostructures

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With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry, Professor Sara Skrabalak at Indiana University – Bloomington will develop new ways of making multimetallic materials with nanoscale dimensions. Metal particles with nanoscale dimensions have fascinating properties that differ from bulk materials. For example, bulk gold appears as a lustrous yellow color while nanoscale gold can appear many different colors depending on particle size and shape, having given rise to the brilliant colors of stained glass. The nanoscale properties of metal particles are now being leveraged in technologies that promote sustainability, security, health, and more. However, general syntheses for nanoscale particles composed of two or more metals are far less developed. The Skrabalak group aims to develop predictable and generalizable syntheses for multimetallic nanoparticles with defined structural and compositional features. This project will provide robust training for graduate students in an inclusive environment. In addition, this research will be coupled with broad educational and outreach initiatives that promote understanding of nanoscale materials, including exploration of the importance of scale through the “Powers of Ten” concept with local artists and non-scientists. Professor Skrabalak and her students will work with the Art Commission of Bloomington, Indiana to identify a site and artist for the creation of a public mural that explores size and scale and their importance to public life. Activities for the public’s exploration of this topic will be developed for use during the mural’s debut and subsequent outreach events.The synthesis of multimetallic nanoparticles will start with known nanoparticles, which will then be converted into more complex nanoparticles by physical and chemical methods. The nanoparticle conversion pathways will focus on two nanoparticle classes. First, high entropy alloy metal nanoparticles – multi-element, single-phase materials consisting of five or more elements in similar atomic ratios – will be synthesized by heating core@shell nanoparticles to facilitate interdiffusion. The mechanism that accounts for their formation will be determined by monitoring changes in crystal phase and elemental distribution. New compositions also will be targeted. Second, nanoparticle heterostructures with different metal domains will be synthesized by galvanic replacement between multimetallic nanoparticles and metal precursors. The mechanism that accounts for the formation of different nanoparticle heterostructures will be elucidated to achieve particles with integrated atomic and nanoscale architectures. The compositional and structural properties of these complex nanoparticles will also be studied.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.