Converting CO2 to carbon at mild conditions

An international research team led by RMIT University (Melbourne, Australia; www.rmit.edu.au) has developed a technique for efficiently converting CO₂ to carbon. The team included researchers from the University of Münster (Germany), Nanjing University of Aeronautics and Astronautics (China), North Carolina State University (Raleigh), University of New South Wales (Sydney, Australia), the University of Wollongong (Wollongong, Australia), and Monash University (Melbourne, Australia).

The storage of CO₂, either in its gaseous state or compressed into a liquid, has proved challenging and costly. Therefore, converting CO₂ into a solid offers an attractive alternative method for safely and permanently removing CO₂ from the atmosphere.

To date, CO₂ has only been converted into a solid at extremely high temperatures, making it industrially unviable. The team created a liquid metal electrocatalyst that contains metallic elemental cerium nanoparticles, which facilitate the reduction of CO₂ to layered solid carbon, at a low onset potential of –310 mV. The formation of a cerium oxide catalyst at the liquid metal/electrolyte interface, together with cerium nanoparticles, promoted the room-temperature reduction of CO₂. The electrode proved remarkably resistant to deactivation via coking caused by the solid carbon.

An extra benefit of the team’s process is that the carbon can hold electric charge, making it a supercapacitor. The process also produces synthetic fuel as a byproduct. The research was conducted at RMIT’s MicroNano Research Facility and the RMIT Microscopy and Microanalysis Facility, with lead investigator, professor Kourosh Kalantar-Zadeh.