Carbon dioxide converted to fuel in efficient new recycling process

A new process has boosted the efficiency of carbon dioxide-to-ethylene conversion, providing a promising route for repurposing excess amounts of the greenhouse gas.

Led by University of Illinois Urbana-Champaign chemistry professor Andrew Gewirth and graduate student Xinyi (Stephanie) Chen, researchers introduced an electrochemical reaction enhanced by polymers to improve efficiency.

Allowing CO₂ to flow through a reaction chamber fitted with copper electrodes and an electrolyte solution is the most common method researchers use to convert the gas into useful carbon-containing chemicals, the team said.

“Copper metal is highly selective toward the type of carbon that forms ethylene,” Gewirth said. “Different electrode materials will produce different chemicals like carbon monoxide instead of ethylene, or a mix of other carbon chemicals. What we have done in this study is to design a new kind of copper electrode that produces almost entirely ethylene.”

Previous studies have used other metals and molecular coatings on the electrode to help direct the CO₂-reduction reactions. However, these coatings are not stable, often break down during the reaction process and fall away from the electrodes, the researchers said.

“What we did differently in this study was to combine the copper ions and polymers into a solution, then apply that solution to an electrode, entraining the polymer into the copper,” Chen said.

In the laboratory, the team found the new polymer-entrained electrodes were less likely to break down and produced more stable chemical intermediates, resulting in more efficient ethylene production.

“We were able to convert CO₂ to ethylene at a rate of up to 87%, depending on the electrolyte used,” Chen said. “That is up from previous reports of conversion rates of about 80% using other types of electrodes.”

Gewirth added: “With the development of economic sources of electricity, combined with the increased interest in CO₂-reduction technology, we see great potential for commercialisation of this process.”

The research was published in Nature Catalysis.

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