A team of energy researchers led by the University of Minnesota Twin Cities has invented a device that electronically converts a metal to behave like another to be used as a catalyst in chemical reactions. The device, called a “catalytic condenser,” is the first to demonstrate that alternative materials that are electronically modified to provide new properties can produce faster and more efficient chemical processing.
The invention opens the door to new catalytic technologies using base metal catalysts for important applications such as renewable energy storage, renewable fuel manufacturing and sustainable materials manufacturing.
The research is published online in JACS Au, where it was selected as an Editor’s Choice publication. The team is also working with the University of Minnesota’s Office of Technology Commercialization and holds a provisional patent on the device.
Over the past century, chemical transformation has relied on the use of specific materials to promote the manufacture of chemicals and materials that we use in our daily lives. Many of these materials, such as the precious metals ruthenium, platinum, rhodium, and palladium, have unique electronic surface properties. They can act as both metals and metal oxides, which makes them essential for controlling chemical reactions.
The general public is probably more familiar with this concept in relation to the upsurge in the theft of catalytic converters from cars. Catalytic converters are valuable because of the rhodium and palladium they contain. In fact, palladium can be more expensive than gold.
These expensive materials are often rare in the world and have become a major obstacle to technological progress.
In order to develop this method of adjusting the catalytic properties of alternative materials, the researchers relied on their knowledge of the behavior of electrons on surfaces. The team successfully tested a theory that adding and removing electrons to one material could transform the metal oxide into something that mimicked the properties of another.
“Atoms really don’t want to change their number of electrons, but we invented the catalytic capacitor device that allows us to adjust the number of electrons on the surface of the catalyst,” said Paul Dauenhauer, a MacArthur Fellow and professor of chemical engineering and materials science at the University of Minnesota who led the research team. “This opens up a whole new opportunity to control chemistry and make abundant materials act like valuable materials.”
The catalytic condenser device uses a combination of nanoscale films to move and stabilize electrons on the surface of the catalyst. This design has the unique mechanism of combining metals and metal oxides with graphene to allow rapid electron flow with tunable surfaces for chemistry.
“Using various thin-film technologies, we combined a nanoscale alumina film made from abundant low-cost metallic aluminum with graphene, which we were then able to tune to take on the properties of other materials,” said Tzia Ming Onn, a postdoctoral researcher at the University of Minnesota who fabricated and tested the catalytic condensers. “The substantial ability to tune the catalytic and electronic properties of the catalyst exceeded our expectations.”
The catalytic condenser design has broad utility as a platform device for a range of manufacturing applications. This versatility comes from its nanoscale manufacturing which incorporates graphene as an enabler of the active surface layer. The power of the device to stabilize electrons (or the absence of electrons called “holes”) is tunable with the varying composition of a highly insulating inner layer. The active layer of the device can also incorporate any base catalytic material with additional additives, which can then be tuned to achieve the properties of expensive catalytic materials.
“We view the catalytic condenser as a platform technology that can be implemented in a multitude of manufacturing applications,” said Dan Frisbie, professor and chair of the Department of Chemical Engineering and Materials Science at the University of Minnesota and research team member. “Basic design ideas and new components can be modified for almost any chemistry we can imagine.”
The team plans to continue research on catalytic condensers by applying them to precious metals for some of the most important sustainability and environmental issues. Several parallel projects are already underway to store renewable electricity in the form of ammonia, manufacture the key molecules of renewable plastics and clean up gaseous waste streams.
Future catalytic converters could give more bang for your buck
Tzia Ming Onn et al, Alumina Graphene Catalytic Condenser for Programmable Solid Acids, JACS Au (2022). DOI: 10.1021/jacsau.2c00114
Provided by the University of Minnesota
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