Precision bond activation with free-atom-like states in single-atom alloy catalysts

Professors Adam Holewinski and Will Medlin of the University of Colorado Boulder are studying catalyst materials that can facilitate the efficient conversion of abundant precursor chemicals into targeted products. The precursors will be derived from agricultural sources and reacted using the catalysts to form compounds needed for pharmaceuticals, plasticizers, fragrances, and flavorings. The proposed work will explore strategies for designing and synthesizing catalyst materials with atomic-level precision, such that their interactions with the precursors are predictable and lead to conversion to desired products with minimal waste byproduct formation. A variety of advanced material and reaction characterization methods will be used to understand the physical phenomena underpinning the performance of the catalysts, allowing for generalization of the findings to inform the design of efficient catalysts for a wide range of economically valuable and societally beneficial chemical and materials manufacturing. In addition to training PhD scientists for the workforce, Holewinski and Medlin will facilitate research opportunities for undergraduates through a structured summer research program and develop educational materials in the form of interactive web experiments targeted for broad use by undergraduate and high school chemistry students. Professors Adam Holewinski and Will Medlin of the University of Colorado Boulder are studying heterogeneous catalysts for the selective transformation of specific bonds. Transition metals are often catalytically active but poorly selective due to energetically broad d-electron states, which can hybridize with multiple molecular orbitals of a substrate. In certain dilute alloys, weak mixing between constituent metal wavefunctions creates energetically narrow, “free-atom-like” electronic states. The proposed work will examine how these narrow states hybridize with molecular orbitals and steer reaction selectivity. Experiments will focus on selective reduction of alpha,beta-unsaturated aldehydes. Operando X-ray spectroscopies will be used, among other techniques, to understand how the electronic and geometric structure of the catalysts influence reaction performance. Insights from this work could impact many chemo- or regioselectivity problems, advancing the manufacturing of compounds that are valuable for pharmaceuticals, plasticizers, fragrances, and flavorings. In addition to training PhD scientists for the workforce, Holewinski and Medlin will facilitate research opportunities for undergraduates through a structured summer research program and develop educational materials in the form of interactive web experiments targeted for broad use by undergraduate and high school chemistry students. 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.