Scientists at Tennessee’s Oak Ridge National Laboratory found a way to turn carbon dioxide into ethanol by accident.

“We discovered somewhat by accident that this material worked,” said the laboratory’s Adam Rondinone, lead author of the team’s study published in ChemistrySelect. “We were trying to study the first step of a proposed reaction when we realized that the catalyst was doing the entire reaction on its own.”

The team used a catalyst comprised of carbon, copper, and nitrogen and applied voltage to trigger a complex chemical reaction that reverses the combustion process. Assisted by a nanotechnology-based catalyst that contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent. Typically, this type of electrochemical reaction results in a mix of several different byproducts in small amounts.

“We’re taking carbon dioxide, a waste product of combustion, and we’re pushing that combustion reaction backwards with very high selectivity to a useful fuel,” said Rondinone. “Ethanol was a surprise. It’s extremely difficult to go straight from carbon dioxide with a single catalyst.”

Rondinone said by using common materials and arranging them with nanotechnology, he and his team were able to limit side reaction and end up with what they really wanted – the ethanol.

The initial analysis indicates that the spiky textured surface of the catalysts provides ample reactive sites to facilitate the carbon dioxide-to-ethanol conversion.

“They are like 50-nanometer lightning rods that concentrate electrochemical reactivity at the tip of the spike,” Rondinone said.

The technique relies on low-cost materials and can be conducted at room temperature in water, so the researchers believe it could be scaled up for industrially relevant applications. For example, it could be used to store excess electricity generated from variable power sources like wind and solar.

“A process like this would allow you to consume extra electricity when it’s available to make and store as ethanol,” said Rondinone. “This could help to balance a grid supplied by intermittent renewable sources.”