The chemical and thermal stability of metal oxides make them ideal materials for harsh environments and for supporting metals as catalysts in applications such as fuel cells or refinement of chemicals. Under some conditions, the oxide support plays as active role in the chemical process, and in this case understanding the oxide properties is crucial for developing new catalytic systems and determining how they work. Under high oxygen pressure, the metal catalyst particles can oxidize and react with their oxide support to form a mixed metal oxide surface layer to create a system that is very different than that observed on bulk materials. In this collaborative project between the University of South Florida and Pennsylvania State University, Drs. Batzill, Janik and Van Duin are coupling sensitive surface characterization techniques with computational modeling methods that predict the formation of mixed metal oxide surfaces formed by oxidizing transition metals deposited on oxide supports. They predict the oxide phase stability and reactivity in heterogeneous oxidation catalysis, and in the process discover some new catalytic materials with interesting and superior chemical catalytic properties. This research project provides training opportunities for students at high school, undergraduate and graduate levels, and establishes collaborations with Brookhaven National Laboratory. Furthermore, the project is working with existing University programs to increase the number of underrepresented science and engineering advanced degree students.
With this award, the Macromolecular, Supramolecular and Nanochemistry (MSN) Program of the Chemistry Division is funding Dr. Batzill of the University of South Florida and Drs. Janik and van Duin of Pennsylvania State University for the investigations of surface-confined mixed-metal oxide phases. The oxide phase of late transition metals in heterogeneous catalysts are the active phase for certain oxidation reactions. The interaction of these oxide phases with another metal oxide support has the potential to lead to novel mixed surface phases that provide additional tunable redox functionality for transition metals supported on oxides. In this project, single atomic layers of oxidized transition metals (e.g. Pd, Co, Ni) are supported on thermodynamically more stable oxides (e.g. ZnO, TiO2) and their stability and chemical functionalities are explored. Combining advanced first principles density functional theory methods with new developments in reactive force field (ReaxFF) Monte Carlo simulations enables them to span length- and time-scales to reach conditions relevant for describing these complex systems in gas environments of various oxygen chemical potentials. Reliable computational tools are essential for screening of materials systems that support the kind of novel monolayer catalysts that then are synthesized and studied experimentally. Single crystalline oxide samples are prepared by pulsed laser deposition under various oxidation environments. The monolayer oxides are investigated with state-of-the-art scanning probe microscopy methods and their chemical functionality probed by a modified molecular beam experiment. Integration of predictive computational tools with experimental verification provides a framework for a quantitative description of the formation of novel single atomic layer, chemically-active oxide phases. This research project provides training opportunities for students at high school, undergraduate and graduate levels, and establishes collaborations with Brookhaven National Laboratory. Furthermore, the project works with existing University programs to increase the number of underrepresented science and engineering advanced degree students.
