One Atom Makes a Big Difference

Illustration by Katie McKissick

Carbon dioxide—CO₂. We exhale it with every breath. Plants use it during photosynthesis to make sugars. Our cars belch it out as we drive—unless that car is electric, of course. It’s the greenhouse gas to blame for climate change.

Carbon monoxide—CO—is an entirely different beast. While it only differs from everyday carbon dioxide by one oxygen atom, it’s highly toxic. It can be produced by combustion when there isn’t sufficient oxygen to produce carbon dioxide, such as in an oven or a car in a closed garage—places where the air is not good for breathing, to say the very least. It’s a colorless and odorless gas, which is why houses and offices are outfitted with carbon monoxide alarms. However, these alarms simply alert occupants if carbon monoxide is present. What if there was a way to isolate carbon monoxide from carbon dioxide? Part of the challenge is that the highly toxic carbon monoxide is often mixed in with everyday carbon dioxide.

Researchers in the lab of Professor Andrea Armani in the Mork Family Department of Chemical Engineering and Materials Science at USC Viterbi are finding a solution.

Left: Rendering of the optical sensor. In this device, circulating light interacts directly with the carbon nanotube clusters on the surface, creating a detectable signal. Middle and Right: Scanning electron microscope image of the optical sensor surface showing the carbon nanotube clusters.

Maria Chistiakova, a chemical engineering Ph.D. student in the Armani Lab, is developing new tools to study the interactions between gases and surfaces. One potential application could be the development of a selective filter for carbon monoxide and carbon dioxide. In her work, she demonstrated that carbon monoxide and carbon dioxide have very different adhesion to carbon nanotubes. While this behavior had been previously shown under vacuum, her device was able to detect this behavior under normal—or real-world—conditions. The ability to perform this measurement under everyday conditions could have wide-ranging implications.

“While the CO/CO₂ experiments have clear applications, Maria’s research could result in advancements in a range of fields,” Armani said. “For example, the design of more robust coatings for aircraft or cars or new materials for gas filters beyond the CO-CO₂ system.”

Illustration by Katie McKissick

This work was published in “Nanotechnology” and is featured on nanotechweb.org.