Spiky catalyst converts CO2 to fuel

IN a moment of scientific serendipity, researchers have uncovered a catalyst that converts carbon dioxide into ethanol at ambient temperature and pressure.

The electrochemical process developed by researchers at Oak Ridge National Laboratory in the US uses a catalyst formed from copper nanoparticles embedded in carbon spikes that converts carbon dioxide dissolved in water into ethanol with a yield of 63%.

“We discovered somewhat by accident that this material worked,” said research leader Adam Rondinone. “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,” Rondinone said. “Ethanol was a surprise – it’s extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst.”

In their research paper discussing the breakthrough, the team noted that while copper is arguably the best-known catalyst for electrochemical reduction of carbon dioxide, the efficiency and selectivity for converting it into other valuable products has until now proved far too low for practical use. This is because competing side reactions have limited the yield of any single liquid product to single digit percentages – far below the 63% achieved at Oak Ridge.

Early analysis suggests that it’s the catalyst’s spiky surface – providing ample reactive sites – that helps drive the conversion.

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

As the catalyst does not require precious metals, and operates in water at room temperature and pressure, the researchers believe it could be scaled up for “industrially relevant applications”. They suggest it could be used to store excess electricity from the grid, such as converting unused electricity from wind power into liquid fuel.

“This could help to balance a grid supplied by intermittent renewable sources,” Rondinone said.
The team plans to refine its approach to improve the overall production rate and further study the catalyst’s properties and behaviour.

Chemistry Select: doi.org/f3rmmr