Combining Nonequilibrium Chemistries with Atomic Precision
Abstract
A great many commodity and high-value chemicals are vital to civilian life and critical to the wide range of technological needs of the Department of Defense. Current chemical processes are typically plagued by the need for large energy consumption, to overcome high reaction barriers, and multiple reaction pathways, requiring additional slow and costly separation procedures to obtain the desired product in pure form. This project brings together two distinct breakthroughs with the potential to revolutionize chemistry. Driving chemical reactions with light, by exciting optically active, metallic plasmonic nanoparticles with chemically reactive sites on their surfaces, has been shown to lower reaction temperatures by hundreds of degrees relative to the analogous thermal process. Second, the creation of reactive sites that consist of single atoms on a catalyst host will enable reaction selectivities of 100% for processes that typically result in multiple reaction outcomes under conventional catalysis. This project combines nonequilibrium chemistries driven by illuminated nanoparticle antennas with the specificity of single-atom reactive sites. Our multidisciplinary team encompasses experimental and theoretical experts in both plasmonic photocatalysis and single-atom catalysis, individuals who have pioneered both areas, to work on merging these two fields. Our goal is to develop a substantially greater understanding of the actual chemical mechanisms provided by the nonequilibrium, excited state reaction pathways of plasmonic photocatalysis, and the bond specificity and reaction selectivity achieved with single-atom reactive sites. Our experimental studies include the synthesis of single-atom alloys, with individual metal atom reactive sites in metal surfaces, and single-atom catalysts, with individual metal atoms on metal oxide surfaces. Both systems will be probed using atomic-scale imaging and spectroscopies, to obtain valuable information on reactive site geometries and electronic structures, to advance our understanding of chemical bond activation at these sites. These studies will be further enhanced by the use of time-resolved spectroscopic methods, to obtain a deeper understanding of the kinetics of charge and energy transfer to adsorbate molecules undergoing chemical transformations. Our theoretical team will provide unparalleled insight and capabilities in the understanding of light-driven processes at nanoparticle surfaces and excited-state bond activation, through charge and energy transfer, at single reactive atomic sites. We will study a range of bond activation processes and chemical transformations that are of direct interest to the Department of Defense. In addition, both plasmonic photocatalysis and single-atom catalysts have been shown to eliminate coking, a deleterious process that reduces lifetimes of conventional catalysts and, more universally, results in carbonaceous deposits in high performance equipment that can lead to catastrophic failures. The studies undertaken in this project will result in more selective chemical reactions with reduced reaction barriers by utilizing light, instead of heat, as the energy input. These studies may also lead to new innovations in processes, materials and coatings that may eliminate or greatly reduce coking or other deposition processes, prolonging the operating cycles of vehicles and other systems of critical importance to the Department of Defense.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410178
Entities
People
- Naomi J. Halas
Organizations
- Air Force Office of Scientific Research
- Rice University
- United States Air Force