Many people won’t look beyond jewelry and coinage for the most important usage of precious metals, but chemical engineers know that precious metals like gold, silver, platinum, palladium, rhodium, ruthenium, iridium and osmium have many more valuable uses.
Solar and other fuel cells, batteries, electronics, drugs, after shaves, bandages and even traditional photography have some reliance on precious metals.
Of particular interest to chemical engineers are their uses as chemical catalysts. But, being precious, chemical reactions that require large volumes of the metals are naturally going to be expensive and unsustainable.
One of the solutions is to use computational modeling below the nanoscale level to design more efficient and affordable catalysts from gold. And a transatlantic alliance of three universities have collaborated to achieve just that.
Researchers from University College London (UCL), University of Pittsburgh Swanson School of Engineering, and University of Delaware have recently published their findings in Catalysis Science and Technology, led by principal investigator, Giannis Mpourmpakis.
Giannis, an assistant professor of chemical and petroleum engineering at the Swanson School, says: “Gold has been widely used as jewelry since ancient times because it does not corrode and keeps its bright yellow color.
“However, subnanoscale catalysts consisting of only a few gold atoms show very rich and difficult to understand chemistry and finding the right composition requires trial and error experimentation in the lab.
“For example, a catalyst that consists of eight gold atoms can be extremely active for oxidation reactions, whereas the catalyst of six gold atoms is not active at all. This behavior has puzzled many researchers over the last decade.”
These new computational modeling methods reduce the time and expense of lab experimentation and allow for more precise predictions of how to design a better catalyst using minute amount of metal to reduce its cost.
Typical reactions on platinum catalysts would require thousands of atoms of rare metal, while the same reaction utilising gold might require fewer than ten.
The greatest potential impact for this process would be in energy-and-environment-related fields, such as the catalytic reactions that convert carbon monoxide to carbon dioxide in automobile exhaust and the production of hydrogen using water and carbon monoxide.
UCL’s Michail Stamatakis, a lecturer of chemical engineering at the university and a co-author of the research, said: “Our study unravels a high degree of complexity in the catalytic behavior of small gold clusters.
“We were very excited to reveal many competing physicochemical phenomena on the catalyst that give rise to the activity of specific catalyst sizes.”
It’s a double celebration for the research team with the Royal Society of Chemistry featuring their research: ‘Catalysis at the sub-nanoscale: complex CO oxidation chemistry on a few Au atoms’ (DOI: 10.1039/C4CY01295J) on the cover of its January issue of Catalysis Science and Technology.