In a world-first, a research team led by RMIT University in Melbourne has used liquid metals to turn carbon dioxide back into solid coal.

Current technologies for carbon capture and storage focus on compressing CO2 into a liquid form, transporting it to a suitable site and injecting it underground. However, implementation has been hampered by engineering challenges, issues around economic viability and environmental concerns about possible leaks from the storage sites.

Converting CO2 into a solid could be a more sustainable approach, according to RMIT researcher Dr Torben Daeneke.

“While we can’t literally turn back time, turning carbon dioxide back into coal and burying it back in the ground is a bit like rewinding the emissions clock,” says Daeneke.

“To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable. By using liquid metals as a catalyst, we’ve shown it’s possible to turn the gas back into carbon at room temperature, in a process that’s efficient and scalable. While more research needs to be done, it’s a crucial first step to delivering solid storage of carbon.”

How it works

Fellow RMIT researcher Dr Dorna Esrafilzadeh developed the electrochemical technique to capture and convert atmospheric CO2 to storable solid carbon.

To convert CO2, the researchers designed a liquid metal catalyst with specific surface properties that made it extremely efficient at conducting electricity while chemically activating the surface.

The carbon dioxide is dissolved in a beaker filled with an electrolyte liquid and a small amount of the liquid metal, which is then charged with an electrical current. The CO2 slowly converts into solid flakes of carbon, which are naturally detached from the liquid metal surface, allowing the continuous production of carbonaceous solid.

According to Esrafilzadeh, the carbon produced could also be used as an electrode.

“A side benefit of the process is that the carbon can hold electrical charge, becoming a supercapacitor, so it could potentially be used as a component in future vehicles,” she says.

“The process also produces synthetic fuel as a by-product, which could also have industrial applications.”

The research has been published in scientific journal Nature Communications.

Image credit: Pixabay

Architecture & Design Team

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