New catalyst can convert carbon dioxide and water into ethanol

Credit: Argonne National Laboratory.

Scientists have discovered a new electrocatalyst that can consistently convert carbon dioxide and water into ethanol with very high energy efficiency and low cost.

Because carbon dioxide is a stable molecule, transforming it into a different molecule is normally energy intensive and costly.

But the new process can electrochemically convert the carbon dioxide emitted from industrial processes—such as fossil fuel or alcohol fermentation plants—into a valuable commodity at reasonable cost.

Ethanol is an ingredient in nearly all U.S. gasoline and is widely used as an intermediate product in the chemical, pharmaceutical and cosmetics industries.

“The process resulting from our catalyst would contribute to the circular carbon economy, which entails the reuse of carbon dioxide,” said Di-Jia Liu, senior chemist in Argonne’s Chemical Sciences and Engineering division and a UChicago CASE scientist in the Pritzker School of Molecular Engineering at the University of Chicago.

The findings were published recently in the journal Nature Energy.

The team’s catalyst consists of atomically dispersed copper on a carbon-powder support.

By an electrochemical reaction, this catalyst breaks down carbon dioxide and water molecules and selectively reassembles the broken molecules into ethanol under an external electric field.

Previous attempts at this process often aren’t very good at fully converting the carbon dioxide. But the electrocatalytic selectivity, or “Faradaic efficiency,” of the new method is over 90%—much higher than any other reported process.

What’s more, the catalyst operates stably over extended operation at low voltage.

“We could couple the electrochemical process of carbon dioxide-to-ethanol conversion using our catalyst to the electric grid and take advantage of the low-cost electricity available from renewable sources like solar and wind during off-peak hours,” Liu said.

Because the process runs at low temperature and pressure, it can start and stop rapidly in response to the intermittent supply of the renewable electricity.

“We have prepared several new catalysts using this approach and found that they are all highly efficient in converting carbon dioxide to other hydrocarbons,” said Liu.

“We plan to continue this research in collaboration with industry to advance this promising technology.”

The team’s research benefited from the Advanced Photon Source and Center for Nanoscale Materials at Argonne, as well as its Laboratory Computing Resource Center.

“Thanks to the high photon flux of the X-ray beams at the APS, we have captured the structural changes of the catalyst during the electrochemical reaction,’’ said Tao Li, an assistant professor in the Department of Chemistry and Biochemistry at Northern Illinois University and an assistant scientist in Argonne’s X-ray Science division

“With this research, we’ve discovered a new catalytic mechanism for converting carbon dioxide and water into ethanol,” said co-author Tao Xu, a professor in physical chemistry and nanotechnology from Northern Illinois University.

“The mechanism should also provide a foundation for development of highly efficient electrocatalysts for carbon dioxide conversion to a vast array of value-added chemicals.”

In addition to Liu and Xu, authors include Haiping Xu, Dominic Rebollar, Haiying He, Lina Chong, Yuzi Liu, Cong Liu, Cheng-Jun Sun, Tao Li, John V. Muntean and Randall E. Winans.

Original study