A "practical starting point" on the road to carbon neutrality

Researchers have discovered what they call "a practical starting point" for converting carbon dioxide (CO2) into sustainable liquid fuels.

In a newspaper in the newspaper Nature Energy, a team from Stanford University in the United States, and the Technical University of Denmark (DTU) explain how electricity and a "very rich catalyst in the ground" can convert CO2 into carbon monoxide (CO ) rich in energy more efficiently than conventional methods.

The key, they say, is that the catalyst – the cerium oxide – is much more resistant to degradation.

And the potential is to produce a carbon neutral product that is a viable alternative to the electrification of transportation systems – not to mention other products such as synthetic gas and plastics.

"We have shown that we can use electricity to reduce CO2 in CO with a 100% selectivity and without producing the unwanted byproduct of solid carbon," says William Chueh, one of the top three authors of the Stanford document.

Researchers say that a way to convert CO2 into CO has not been widely marketed yet due to various performance issues encountered in previous attempts. Their first step was therefore to analyze how and why different devices had succeeded and failed in CO2 electrolysis.

They then built two cells to test CO2 conversion: one with cerium oxide and the other with conventional nickel catalysts. The cerium oxide electrode remained stable, while carbon deposits damaged the nickel electrode, greatly shortening the life of the catalyst.

"This remarkable ability of ceria has major implications for the practical life of CO2 electrolysers," says Christopher Graves of DTU.

"Replacing the current nickel electrode with our new cerium oxide electrode in the next generation of electrolyser would improve the life of the device."

Researchers say that the removal of carbon accumulation allows their new device to convert a greater amount of CO2 into CO and thus improve the concentration of CO products less than 50% common to current cells . This, they add, could reduce production costs.

"The mechanism of carbon removal on cerium oxide relies on carbon sequestration in stable oxidized form," said lead author Michal Bajdich.

"We were able to explain this behavior with computer models of CO2 reduction at high temperature, which was then confirmed by X-ray photoelectron spectroscopy of the operating cell."