ABSTRACT

Franklin (Feng) Tao of the University of Notre Dame is funded through this CAREER award by the Chemical Catalysis program for research to develop new types of catalysts. These catalysts show promising abilities to remove poisonous gases such as nitrous oxide from exhaust. The new catalysts being developed through this research consist of metal atoms bonded to an oxide support. A unique feature of this work is the small size of the metal clusters. Good results have been obtained from a system consisting of a single rhodium atom bonded to two cobalt oxide molecules. These systems are much smaller than those typically used in industrial work and this size advantage could lead to improved properties. The investigators are extending earlier research with rhodium atoms to include other precious metals, in particular palladium and platinum, with the hopes to further improve catalytic activity. The broader impacts of this project include the development of new efficient catalysts that could be used to generate new chemical fuels or to remove gaseous contaminants from the environment. The project is having a further impact on the education and training of the next generation of scientists, including very young scientists still in high school who are participating in outreach efforts of the research team.

The catalysts being developed are heterogeneous, which means that the catalytic event occurs on a catalytic site consisting of atoms of metal, support, or both. In this research, bimetallic catalyst particles are being investigated. These are two-atom clusters (dimers, in other words), which typically consist of continuous bimetallic sites that have a size in the nanometer range. In the systems studied here, which are singly dispersed bimetallic sites, the catalytic sites are isolated rather than continuous and thus exhibit a different electronic state and molecular adsorption. The specific binding configuration of a reactant molecule or intermediate on an isolated bimetallic site has been found to enhance catalytic selectivity for specific products. The current project focuses on the development of catalysts of singly dispersed bimetallic sites of 3d-4d and 3d-5d metals. Good results have already been found with RhCo2 clusters. Additional studies are being carried out with Pd and Pt, in addition to Rh, combined with both cobalt and zinc oxide supports.

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