Accidentally discovered catalyst strips CO2 from air

In what could be called as an accidental discovery, chemists have found a catalyst that strips only carbon dioxide from the air - ignores oxygen - and converts it into a useful compound.

However, the copper-based compound is still far from being a practical air-scrubber for removing CO2, because the catalyst takes hours to be recycled to its original state.

But the innovative chemistry has led scientists to believe that a catalyst could one day selectively and efficiently remove the greenhouse gas from the air, turning it into organic chemicals.

Many catalysts with a structure based around a metal centre - such as a copper atom - can grab CO2 from a pure stream of the gas, but when in contact with air, they prefer to couple with the more abundant and more reactive oxygen.

So the selectivity of the new compound is "completely unexpected", Nature quoted Elisabeth Bouwman at Leiden University in the Netherlands, who led the team that discovered the catalyst, as saying.

The researchers were investigating compounds that mimicked the activity of biological enzymes.

Bouwman took the chemical shell off the nickel centre of one such mimic, and tried wrapping it around copper for comparison.

But, she noticed that this structure produced a yellow solution, which turned green-blue after sitting in the open air for a few days.

Analysis of the green-blue product showed that it contains a segment called oxalate - made of two CO2 molecules - which form a bridge linking two copper atoms together.

This fragment could occur only if CO2, not oxygen, had oxidized the copper compound.

Bouwman said that she doesn't know why the copper complex prefers CO2 to oxygen, but it could be because the oxalate bridge within the molecular structure of the green-blue product is extremely stable.

The study's results have been published in Science1.