DMREF/Collaborative Research: Design of Multifunctional Catalytic Interfaces from First Principles

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Abstract Title: DMREF: Collaborative Research:Design of next-generation catalysts through predictive modeling and atomic-scale experimentsCatalysts are the materials that allow the production of critical substances that make modern life possible. Catalytic technologies make essential contributions to many sectors of the US economy, ranging from petrochemicals processing to pollution abatement in automobiles, and many products that are taken for granted in contemporary society would not exist without these crucial processes. Traditional strategies for the discovery of new heterogeneous catalysts have relied heavily on chemical intuition and experience accumulated over many years of industrial practice, but to develop the next generation of catalytic materials, these strategies will be inadequate. The collaborative team of Profs. Jeffrey Greeley, Volkan Ortalan, and Fabio Ribeiro of Purdue University, and Chao Wang of Johns Hopkins University, have been awarded a grant under the National Science Foundation Designing Materials to Revolutionize and Engineer our Future (DMREF) initiative to develop a new strategy. The team proposes to make accurate predictions from a combination of experiments with atomic-level resolution and modeling using large-scale computing. Such predictive techniques have been explored for simple classes of catalytic materials, such as highly ordered metal or oxide surfaces. However, a much broader space of potentially exciting catalysts can be accessed by exploring so-called "multifunctional" materials, which offer complex interfaces between metals and oxides. The researchers will combine unparalleled atomic-scale experimental characterization, synthesis, and reactivity measurements to both inform the computational models and test predicted catalysts to emerge from the computational analysis. The proposed program will both lay the fundamental groundwork for accelerated identification of breakthrough catalytic materials, in general, and identify practical new catalysts for reactions with CO, CO2, and H2 as feedstocks, in particular.Single component heterogeneous catalysts are constrained by inherent limitations in catalytic rates, as exemplified by the well-known maxima in volcano plots that have been observed for many catalytic chemistries. The limitations can, in turn, be traced to an extensive series of fundamental correlations that exist between the energetics of elementary steps and species on the sites in question. Multifunctional catalytic structures, such as the interfaces that exist between thin oxide films and metal nanoparticles, provide a potential means of overcoming these limitations and identifying entirely new classes of catalysts. Developing a unified design framework for such multifunctional structures will require a combination of first principles molecular modeling techniques, advanced methods to synthesize and characterize the structure of catalysts at the atomic scale, and highly accurate measurements of reaction rates on the resulting materials. The project team will focus on model reactions, relevant to hydrogen production and methanol synthesis, which can be promoted at multifunctional interfaces. The team will develop new molecular modeling strategies, relying primarily on ab-initio methods, to rapidly evaluate the catalytic properties of many combinations of metal/oxide interfaces for the reactions of interest. Promising candidates to emerge from these computational screening studies will then be synthesized using techniques that permit control of the catalyst structure at the atomic level. The catalytic and structural properties of these catalysts will be verified experimentally at atomic resolution, and the resulting information will be used to improve the predictive models and to further refine the candidate materials. The end goal is a method of broad applicability that can be used to design breakthrough multifunctional catalytic materials for a variety of reactions of scientific and economic importance.