CAS: Designing Copper-based Multi-metallic Single-atom Alloys for Cross Coupling Reactions through Combined Surface Science and Catalytic Investigations

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With the support of the Chemical Catalysis program in the Division of Chemistry, Nathaniel Eagan and Charles Sykes of Tufts University are studying the catalytic behavior of novel catalysts comprising trace amounts of two dopant metals present as single atoms, embedded in the surface of a third host metal. The team will combine macroscopic-scale studies of actual catalysts with atomic-scale studies of single-crystal models. The novel catalysts consist of two different metals, isolated as single atoms, on a third metal, a composition referred to as “trimetallic single-atom alloys.” Prior studies with bimetallic single-atom alloys, e.g., two metals, have shown that the isolated atoms drive uniquely efficient and selective catalysis of many important chemical transformations. By adding a third metal, Eagan and Sykes aim to perform more challenging chemistries, such as carbon-carbon coupling reactions crucial to a wide range of chemical syntheses. Dr. Eagan and his students will synthesize trimetallic single-atom alloy catalysts, characterize their structures using a wide range of analytical techniques, and examine their catalytic behaviors in laboratory-scale chemical reactors. Dr. Sykes and his students will synthesize the single-crystal models and investigate them using ultra-high vacuum techniques to probe structures at the atomistic level and correlate them with catalytic properties. This project aims to provide fundamental new knowledge from which a wide range of trimetallic single-atom alloys could be produced and implemented in catalyst syntheses. This project will also support efforts to connect the chemistry and chemical engineering disciplines at both the K-12 and university levels through the development of nanoscience activities and university courses.Trimetallic single-atom alloys are designed to leverage the unique chemistries exhibited by distinct isolated metal atoms embedded within low-reactivity, high-selectivity coinage metal hosts in tandem catalysis on a single catalytic surface. These systems balance the diverse needs of complex surface reactions which possess elementary steps with vastly differing catalytic requirements, as is the case for many carbon-carbon coupling reactions. Eagan and Sykes will investigate mechanisms by which spillover of chemical intermediates between distinct dopant atoms enables them to cooperatively act on different parts of a catalytic cycle and drive a wider range of chemistries than would be available from bimetallic single-atom alloys. Surface science studies performed by Sykes will provide details of the geometric and electronic structures of these materials with atomic resolution as well as quantification of the kinetics of elementary reaction steps. Eagan will bridge these studies to more industrially relevant conditions in catalytic reactors through microkinetic modeling and reactor studies with catalysts synthesized using well-controlled colloidal methods. Understanding the dynamic structures of these materials in the two environments, and situations in which they do and do not affect each other, are embedded targets of these studies. This collaborative work aims to understand and bridge the materials, pressure, and temperature gaps that exist between our surface science and catalytic reactor approaches thereby generating fundamental new insights and methodologies to advance the development of this novel class of trimetallic single-atom alloy catalysts.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.