Probing metal catalyst-support interactions using small cluster models: Gas-phase reactivity studies, anion photoelectron spectroscopy, and DFT calculations

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The Chemical Catalysis Program supports the efforts of Professor Caroline C. Jarrold from Indiana University to study the interplay between electronic and structural properties of well-defined cluster models used to study the inherently local phenomenon of catalyst-support and catalyst-support-substrate interactions. A three-pronged approach is used to characterize cluster models of new catalysts that have been identified as particularly active toward the industrially-important water-gas shift reaction. (The water gas shift reaction catalytically combines water and carbon monoxide to produce dihydrogen and carbon dioxide.) Anion photoelectron (PE) spectroscopy measurements on model clusters provide a mass-specific electronic profile of the clusters as a function of both metal composition and oxygen content. Cluster structures are determined by reconciling experimental PE spectra with computational results and gas-phase reactivity studies on the clusters allow for the correlation between cluster reactivity and cluster molecular and electronic structures. The first series of studies focus on platinum-containing cluster systems inspired by recent literature. Alternative and less expensive cluster models rationalized to have similar (and possibly improved) attributes are also explored and compared to known industrial catalysts. The broader impacts of these studies include the generation of knowledge that can inform the design of improved, lower-cost and more energy-efficient catalysts for water gas shift reactions and the evaluation of new computational approaches used to study metal oxides in non-traditional oxidation states. In addition, a new generation of scientists are trained to understand industrially-relevant catalysis reactions.Metal oxides are often used as industrial catalysts. Their composition is often optimized so that the catalysts operate at lower temperatures or with cheaper and more readily available materials. This research project is designed to determine the essential molecular-scale features that govern catalysts used in the water gas shift reaction. The water gas shift reaction combines water and carbon monoxide to make dihydrogen and carbon dioxide. Experimental and computational tools are used to create and study the properties of well-defined nano- and sub-nanometer scale bits of metal oxides used in this industrially important reaction. The technical broader implications of this project include a reduced energy consumption for this industrial process. A more immediate and direct outcome of this project is the training of young women and men in the scientific method using computational and experimental platforms centered on a project that motivated by practical industrial concerns.