Researchers turn CO2 into ethanol - by accident
A chemical reaction that converts CO2 into ethanol has been discovered, which could be a new method for mitigating climate change. Researchers at the Oak Ridge National Laboratory in Tennessee stumbled upon the finding while trying to identify a series of chemical reactions that could turn CO2 into a useful fuel. The technique works at room temperature, which means it could be used as temporary energy storage during lulls in renewable energy generation and help balance grids supplied by intermittent renewable sources.

“We discovered somewhat by accident that this material worked,” said ORNL’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 realised that the catalyst was doing the entire reaction on its own.”

“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. Ethanol was a surprise – it’s extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst.”

The catalyst is unique and effective because of its nanoscale structure, which contains copper nanoparticles embedded on carbon spikes. This approach meant that the researchers didn’t need to use expensive or rare metals, such as platinum, which typically push costs up and make the process less economically viable.

“By using common materials, but arranging them with nanotechnology, we figured out how to limit the side reactions and end up with the one thing that we want,” Rondinone added.

The researchers’ initial analysis suggests the spiky textured surface of the catalysts provides multiple sites where the reaction can take place, and ultimately help turn carbon dioxide into ethanol.

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

Given the technique’s reliance on low-cost materials and the fact it can be operated at room temperature in water, the researchers believe the approach could be scaled up. For example, the process could be used to store excess electricity generated from power sources such as wind and solar. The researchers said they will refine their approach to improve production rate and further study the catalyst’s properties.

The work was supported by DOE’s Office of Science and used resources at the ORNL’s Centre for Nanophase Materials Sciences.