The research team led by RMIT University in Melbourne, Australia, developed a new technique using a liquid metal electrolysis method which efficiently converts CO2 from a gas into solid particles of carbon.
Published in the journal Nature Communications, the authors say their technology offers an alternative pathway for “safely and permanently” removing CO2 from the atmosphere.
Current carbon capture techniques involve turning the gas into a liquid and injecting it underground, but its use is not widespread due to issues around economic viability, and environmental concerns about leaks from the storage site.
The new technique results in solid flakes of carbon, similar to coal, which may be easier to store safely.
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 along with a small amount of the liquid metal, which is then charged with an electrical current.
The CO2 slowly converts into solid flakes, which are naturally detached from the liquid metal surface, allowing for continuous production.
RMIT researcher Dr Torben Daeneke said: “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.”
“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.”
Lead author, Dr Dorna Esrafilzadeh said the carbon produced by the technique 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 said.
“The process also produces synthetic fuel as a by-product, which could also have industrial applications.”