An international team of scientists has created a crystal that can efficiently capture carbon dioxide from the air, according to a new study published in Science. The research offers a way to reduce damaging carbon emissions and curb climate change.
The team’s crystalline material, the charismatically-named SGU-29, absorbs carbon dioxide better than any existing material. The breakthrough comes with the crystal’s ability to absorb water and carbon dioxide separately – a feature lacking from other materials. SGU-29 could theoretically reduce carbon emissions by trapping gas in the chimneys of power stations and other facilities.
Crystals like this one have microscopic ‘adsorption sites’ to take up carbon dioxide. Think of them as tiny docking sites for even tinier molecules. Unfortunately, though, in most materials, water molecules dock at the very same sites as carbon dioxide.
“CO2 is always produced with moisture,” explained Osamu Terasaki, Professor at the Department of Materials and Environmental Chemistry at Stockholm University. “In other cases there is competition between water and carbon dioxide, and water usually wins.”
That means that adsorption sites get filled by water, leaving the carbon dioxide in the air. Most crystals therefore only take up carbon dioxide efficiently if the air around them has been completely dehydrated – a rather expensive, unrealistic requirement for real-world scenarios.
But SGU-29, is special: it has separate docking sites for carbon dioxide and water, meaning that moist air does not limit its capacity to absorb carbon dioxide.
“This material adsorbs both, but the CO2 uptake is enormous,” said Terasaki.
Even better, the crystal is long-lived and reusable, making it a candidate for the coating of power plant flues and chimneys. Better still, the scientists say that the trapped, waste carbon could be recycled to make other important materials.
“I think we will be able to do this within five years,” Terasaki said. “The most difficult part is to capture carbon dioxide, and we have a solution for that now.”