Science & Technology

This Dr. Seuss-esque Element Could Turn Carbon Dioxide Into Fuel

If you've never heard of bismuth, get ready to meet your new favorite element. Bismuth crystals look like they were designed by M.C. Escher, forming kaleidoscopic staircases of glittering silver, pink, and gold. But the element isn't just a pretty face: It's used in everything from cosmetics to ammunition to the bottle of Pepto-Bismol in your medicine cabinet. It also may be the answer to rising carbon dioxide levels. New research shows that bismuth has a particularly fascinating property that we can use to turn CO2 directly into liquid fuel.

A Rainbow of Possibilities

Bismuth is a particularly strange and impressive element. Of all the metals, it's the most diamagnetic. That essentially means it's the opposite of a magnet, being repelled by rather than attracted to a magnetic field. It's also one of only a handful of elements that expands rather than contracts when it freezes, the way water does. At the opposite end of the temperature spectrum, bismuth melts surprisingly easily. With a low melting point of 271 degrees Celsius, it's used as the proverbial canary in the coal mine to safeguard against high electric currents in electronics and to detect fire in sprinkler systems. It turns out that bismuth has important applications in chemistry, too.

Lead researcher Joel Rosenthal, a chemistry professor at the University of Delaware, has been studying this wonder element for a while now. The new paper was published in the journal ACS Catalysis in March. The key to this latest breakthrough is what Rosenthal describes as bismuth's "catalytic plasticity," or its ability to convert one compound into any of several others with just a few tweaks. To do that, the team applied an electric current to a bismuth film in a bath of salty liquids. By altering the specific ingredients in that salty bath, the team could "tune" the chemical reaction to convert CO2 into either carbon monoxide or formic acid.

"Both carbon monoxide and formic acid are valuable commodity chemicals that have applications in and of themselves, and can also be used as precursors to produce other valuable chemicals and fuels," Rosenthal explained in an email. Formic acid has a wide variety of industrial uses, from preserving food to manufacturing rubber, leather, artificial flavorings, and perfumes. Even cooler, carbon monoxide can be easily turned into gasoline with technology that already exists.

Lemons Into Lemonade

This is huge because chemists usually need to create a new catalyst — the role that bismuth is playing here — for every chemical reaction they want to study. The new approach lets them use one catalyst they can tweak slightly to create various reactions.

"There are philosophical parallels between catalysis and the goals of the ancient alchemists," Rosenthal said in a statement. "Alchemy is a loaded word, but in some ways, what we are studying is like modern alchemy — efficiently transforming carbon dioxide to more valuable fuels and chemicals is akin to trying to convert lead to gold."

In this case, he's converting a compound that's causing immediate harm to the environment. In April, carbon dioxide reached its highest sustained levels since we started monitoring it, at more than 410 parts per million for the month. If we could use this technology to take CO2 captured from the atmosphere and turn it into useful fuels and chemicals, we might be able to reduce its impact on the environment — and get something beneficial out of it at the same time.

Periodic Table of Videos: Bismuth

Written by Ashley Hamer June 25, 2018
