The precious metals, such as platinum, palladium and rhodium, in catalytic converters make them attractive to thieves, but University of Central Florida researchers are working to reduce the amount of precious metals needed in them — down to single atoms — while still maximizing their effectiveness.
Catalytic converters, which were introduced widely in U.S. vehicles in the 1970s, use precious metals as catalysts to help scrub harmful and deadly chemicals from combustion engine exhaust. As the price of precious metals has risen, so has the number of catalytic converter thefts.
In recent studies appearing in Nature Communications and Journal of the American Chemical Society, UCF researchers showed they could use atomic platinum to control pollutants and operate the system at lower temperatures, which is crucial to removing dangerous chemicals when an automobile starts.
In the Nature Communications study, UCF research teams led by Fudong Liu, assistant professor in the department of civil, environmental and construction engineering, and Talat Rahman, distinguished Pegasus professor in the department of physics, successfully constructed platinum single atoms with different atomic coordination environments at specific locations on ceria. Ceria is a metal oxide that helps improve catalytic reaction performance.
The platinum atoms exhibited strikingly distinct behaviors in catalytic reactions, such as carbon monoxide oxidation and ammonia oxidation in a diesel engine exhaust after-treatment system, researchers say. The oxidation converts deadly carbon monoxide to carbon dioxide and converts harmful ammonia to nitrogen and water molecules.
Liu said results suggest that the catalytic performance of single-atom catalysts in targeted reactions can be maximized by optimizing the local coordination structures through simple, industrial-scalable strategies.
“By combining electronic structure calculations with state-of-the-art experiments,” he said, “the Liu and Rahman teams have made a breakthrough that can significantly benefit the heterogenous catalysis community in designing highly efficient single-atom catalysts for both environmental and energy-related needs. We have successfully developed a facile strategy to selectively fine-tune the local coordination environment of platinum single atoms to achieve satisfactory catalytic performance in different target reactions, which will push the understanding of single-atom catalysis a significant step forward.”
Rahman said the collaborative work demonstrates how theory and experiments working in tandem can unveil microscopic mechanisms responsible for enhancing catalytic activity and selectivity.
— Robert Wells
