Scientists discover new 'cages of cages' molecule that can trap greenhouse gases

Scientists have identified a new sort of porous material that is distinct in its molecular structure and has the potential to be utilised to trap carbon dioxide and another, more potent greenhouse gas. They call this substance a "cage of cages."

The material was created in two phases by scientists in the UK and China using reactions to assemble triangular prism-building pieces into bigger, more symmetrical tetrahedral cages. According to the team, this is the first molecular structure of its sort.

The resultant material has a high affinity for attracting and holding greenhouse gases like carbon dioxide (CO2) due to its abundance of polar molecules. Additionally, it demonstrated outstanding stability in water, which is essential for its application in the industrial context to extract carbon from humid or wet gas streams.

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"We need new porous materials to help solve society's biggest challenges, like capturing and storing greenhouse gasses," says Marc Little, a materials scientist at Heriot-Watt University in Edinburgh and senior author of the paper. "This is an exciting discovery."

The novel cage-like material was also shown to have a high absorption of sulfur hexafluoride (SF6), the most powerful greenhouse gas according to the Intergovernmental Panel on Climate Change, in lab testing, albeit these tests were not conducted at scale.

Researchers are working on new materials to make direct air capture more efficient and less energy-intensive, and this new substance might be one of them.

Even though the precursor molecules may theoretically assemble themselves, it wasn't a simple task to create a material with such tremendous structural complexity. Researchers refer to this method as supramolecular self-assembly. It requires some fine-tuning since "the best reaction conditions are often not intuitively obvious," as Little and colleagues describe in their published research. However, it can create chemically linked structures from simpler building pieces.

The difficulty of synthesis increases with the final molecule's complexity, and those processes may result in more molecular "scrambling."

In addition to its ability to absorb greenhouse gases, the researchers propose that their new material may also be employed for the elimination of other airborne pollutants, such as volatile organic compounds.