CAS: Understanding Catalyst Roles in Aluminum Nanocrystal Synthesis

William Marsh Rice University, Houston TX

Investigators

Abstract

With the support of the Chemical Catalysis Program in the Division of Chemistry, Professor Naomi Halas of Rice University and Professor Ian Tonks of the University of Minnesota are studying how titanium catalysts can control the formation of aluminum nanocrystals with tunable structural and physical properties. Coinage metal nanoparticles are well-known for their optical properties that arise due to their collective electronic resonances, known as surface plasmons. The plasmonic properties of these materials have been shown to support a range of phenomena including surface enhanced spectroscopy and photothermal heating characteristics. While most studies have focused on gold- and silver-nanoparticles, there is growing interest in earth-abundant metals such as aluminum. The synthesis of aluminum nanocrystals is unique because it requires a titanium catalyst. Professors Halas and Tonks are working together with their research teams to determine how these catalysts work and how they can be controlled to form aluminum nanocrystals with predictable structures and function. These collaborative activities will also combine the scientific safety expertise of the two research groups to share best practices across universities and catalysis fields. While the synthetic chemistry of aluminum nanocrystals has only recently begun to be investigated, there is significant interest in preparing these materials due to the earth-abundance and outstanding plasmonic properties of aluminum. The synthesis of aluminum nanocrystals is distinct from noble and coinage metals in that a catalyst is required for nanocrystal nucleation and growth. Professor Halas and Professor Tonks are working together to develop a comprehensive mechanistic picture of aluminum nanocrystal synthesis. Using a combination of kinetic analysis, model systems, and spectroscopy that blends the catalytic expertise of the two research groups, proposed mechanisms for nucleation will be tested, the impact of the catalyst structure on nanocrystal morphology will be investigated, and the relationship between catalyst and nanocrystal structure will be studied. These activities will provide interdisciplinary training for graduate students from both research groups and support the exchange and enhancement of chemical safety culture between both universities. 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.