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New material converts CO2 into clean fuel with unprecedented efficiency

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BEC CREW
8 JAN 2016
 

A new material made from microscopic layers of cobalt can convert carbon dioxide gas into formate - a fuel that can be burned with no toxic byproducts and used as a clean energy source.

Developed by a team of researchers in China, the material could be one way to deal with the 36 gigatonnes of CO2 we release into the atmosphere each year due to fossil fuel use. Scientists have been struggling for decades to come up with an energy-efficient way to transform CO2 into something useful, and early testing points to this new material as being one of the most promising options we’ve seen so far.

 

"This represents a fundamental scientific breakthrough," Karthish Manthiram, a chemical engineer from the California Institute of Technology who was not involved in the research, told William Herkewitz at Popular Mechanics. 

"Certainly it will be a years-long process before this is worked into a successful, commercial device. But at this stage of development, by all conceivable metrics, this reaction looks very positive."

The material is just four atoms thick, and is made up of ultra-thin layers of pure cobalt metal and a cobalt oxide-cobalt metal mix. When it undergoes the process of electroreduction, which involves feeding a small electric current through the material to change the molecular structure of the CO2 inside, it produces a clean-burning fuel.

As Herkewitz explains, when an electric current is applied to the cobalt nanomaterial, it causes the molecules inside the material to interact with the CO2 molecules that are running freely through it. This causes hydrogen atoms to attach to carbon atoms from the CO2, prompting an extra electron to be propelled into one of its oxygen atoms. "With that, the CO2 becomes CHOO-, or formate," he says.

Lab tests with the material confirmed that it can maintain "stable current densities of about 10 milliamperes [of formate] per square centimetre over 40 hours, with approximately 90 percent formate selectivity at an overpotential of only 0.24 volts".

I know you want to, but don’t freak out about what all that actually means just yet.

This "overpotential" is the amount of energy lost due to the slowness of electrochemical reactions sustained by electrodes such as this one. The smaller the overpotential, the better, but in order to make something efficient, it has to maintain that small overpotential while also keeping the rate of fuel production up. This is where many attempts at CO2 electroreduction have fallen short in the past.

Manthiram, who is himself working on his own CO2 electroreduction solutions, told Popular Mechanics that not only can this new material sustain that low overpotential while also achieving a high rate of formate production, it manages to keep everything stable too. "It's very rare and difficult to find a material that satisfies all three of those constraints," he said, adding that this material is "the best we've seen" so far.

The team, from China's Hefei National Laboratory for Physical Sciences, describes the material in the journal Nature. The next step will be to demonstrate how it can be incorporated into commercial technology so we can start using up some of the CO2 that's floating around in our atmosphere, causing trouble

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