Identifying Reactivity Descriptors of Single Atom Catalysts
Abstract
Catalytic low temperature oxidation is important for many applications including pollution abatement (e.g. oxidation of CO and unburned fuel in car exhausts), indoor air quality control (e.g. oxidation of volatile organic compounds such as HCHO, benzene), as well as for breaking down chemical warfare agents. Supported single atom catalysts (SACs) have emerged as a promising class of catalysts for low temperature oxidation. Their efficient use of metals and tunable properties make them ideal to understand reaction mechanisms and structure-reactivity relationships to design better catalysts. However, despite major advances in understanding the properties of SACs, it remains a grand challenge to predict their activity, even for a simple reaction such as CO oxidation. The goal of this work is to identify descriptors to understand the activity trends for low temperature CO oxidation on SACs and to enable the prediction of better catalysts. Our approach combines controlled synthesis, in situ/operando characterization (microcalorimetry, X-ray absorption spectroscopy and infrared spectroscopy), kinetic measurements and ab initio calculations to investigate the structural, electronic and catalytic properties of the selected supported single atom catalysts. Our two main objectives are: 1) determine the effect of metal-support interactions (different metals and support properties) on the reaction mechanism and CO oxidation activity, and 2) investigate the nature of chemical bonding and identify reactivity descriptor(s) for supported single atom catalysts. Expected Outcomes and Impact The results from this work are expected to advance the basic science of single-atom catalysis by revealing unprecedented atomic level details on the role of support reducibility and metal-support interface in affecting the CO oxidation activity and mechanism. Specifically, the close integration between experiments and theory will result in a library of single atom catalysts, with their detailed atomic structures, electronic properties, energetics and nature of the chemical bonding with CO and O2, and identified CO oxidation reaction mechanisms. The proposed catalysts (selected metals and supports with different reducibility and electronic properties) and methodology will allow us to critically examine scaling properties of reaction intermediates and transition states on supported single atom catalysts which can be extended to other systems. If successful, the work will identify, for the first time, descriptors for predicting the activity of supported single atom catalysts and lay the foundation for future work on more complex systems/reactions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 06, 2019
- Source ID
- W911NF1910308
Entities
People
- Ayman M Karim
Organizations
- Army Contracting Command
- United States Army
- Virginia Tech