New tool could lead to more efficient ways to capture carbon

Such carbon-capture technology, developed by researchers at the University of Colorado Boulder, may help limit global warming this century to 1.5°C above pre-industrial temperatures and fend off the catastrophic effects of global climate change.

The method predicts how strong the bond will be between carbon dioxide and the molecule that traps it, known as a binder. Experts can easily apply this electrochemical diagnosis to any molecule that is chemically inclined to bind with carbon dioxide, allowing researchers to identify suitable molecular candidates with which to capture carbon dioxide from the air.

“The Holy Grail, if you will, is to inch toward being able to use binders that can grab carbon dioxide from the air [around us], not just concentrated sources,” said Oana Luca, assistant professor of chemistry at the university. “Determining the strength of binders allows us to figure out whether the binding will be strong or weak and identify candidates for future study for direct carbon capture from dilute sources.”

The goal of carbon capture and storage technology is to remove carbon dioxide from the atmosphere and store it safely for hundreds or thousands of years. But while it has been in use in the US since the 1970s, it currently captures and stores only 0.1 per cent of global carbon emissions annually.

To help meet carbon emissions goals laid out by the Intergovernmental Panel on Climate Change (IPCC), carbon capture and storage would have to increase in scale by 2050.

Current industrial facilities around the world rely on capturing carbon dioxide from a concentrated source, such as emissions from power plants. While these methods can bind a lot of carbon dioxide quickly and efficiently using large amounts of certain chemical binders, they are also energy-intensive.

This method is also quite expensive at scale to take carbon dioxide and turn it into something else useful, such as carbonates, an ingredient in cement, or formaldehyde or methanol, used in fuel, according to Luca.

Using electrochemical methods instead, such as those detailed in the new CU Boulder-led study, would free carbon-capture facilities from being tied to concentrated sources, allowing them to exist almost anywhere.

According to Haley Petersen, a graduate student in chemistry, being able to estimate the strength of chemical bonds also enables researchers to screen the best-suited binders – and offer a cheaper alternative to traditional methods – for capturing and converting carbon into materials or fuel.

In the study, the researchers used electricity to activate covalent bonds by using an electrode to deliver an electrode to a molecule. When they applied this to an imidazolium molecule, this removed a hydrogen atom, creating a gap in a carbon atom for another molecule to want to bond with it – such as carbon dioxide.

However, carbon dioxide is a kind of molecule that is rarely likely to create new bonds. “It’s unreactive, and in order to react to it, you also have to bend it,” Luca explained. “So, we’re in a chemical space not probed before for CO₂ capture.”

The method examines how good a whole family of carbenes (a specific type of molecule, containing a neutral carbon atom) – that can also electrochemically generate – are at binding CO₂.

“Just by looking at very simple molecules – molecules that we can make, molecules that we can modify – we can obtain a map of the energetics for electrochemical carbon capture. It is a small leap for now, but possibly a big leap down the line,” Luca concluded.