Collaborative Research: Beyond the Single-Atom Paradigm: A Priori Design of Dual-Atom Alloy Active Sites for Efficient and Selective Chemical Conversions

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With support from the Chemical Structure, Dynamics, and Mechanisms A (CSDM-A) program in the Division of Chemistry, Matthew Montemore of Tulane University and Charles Sykes of Tufts University are performing computational and experimental investigations of a novel class of dual-atom catalysts using quantum chemistry, machine learning, and atomic-scale characterization. These novel materials, termed dual-atom alloys, consist of an energetically stable pair of different metal atoms embedded in the surface of a host metal. Compared to single-atom alloys, a similar class of materials with well-defined active sites, dual-atom alloy active sites are anticipated to be more reactive and enable more challenging reactions including targeted bond scission. However, accelerating the discovery of novel alloys requires addressing numerous challenges including identifying promising combinations of metals from the large materials space of potential pairings, understanding their structure/function relationships, and creating an effective feedback loop between experiment and computation. Dr. Montemore and his students will use machine learning combined with density functional theory (DFT) to identify candidate structures based on surface stability and low energy barriers for specific chemical reactions. Dr. Sykes and his students will experimentally synthesize, characterize, and test the predicted structures. Their discoveries could lead to the development of an entirely new class of catalysts where well-defined metal atomic structures can be combined with predictive models to accelerate a range of multistep reaction mechanisms. In addition to these broad scientific impacts, this project will also support a virtual reality K-12 outreach workshop, provide mentorship for Hispanic scientists and engineers, and inspire students from underserved high schools by facilitating a Reverse Science Fair.Dual-atom alloys leverage several of the advantages of single-atom alloys: a well-defined active site that allows clear correspondence across computation, surface science, and reactor studies; opportunities to deviate from linear correlations in reaction energetics; and unique electronic structure. Just as with single-atom alloys, in which surface science experiments and computation preceded catalyst synthesis and testing, Montemore and Sykes will couple theory and surface science experiments to explore dual-atom alloy structure-reactivity space. This research is expected to lead to the development of structure-function relationships on a broad set of well-defined active sites, which would then serve as a guide to the larger heterogenous catalysis community. Furthermore, these studies have the potential to uncover new classes of materials with high catalytic performance, a particular need for reactions that are challenging with traditional heterogeneous catalysts, such as selective cross-couplings.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.