Liquid alloy of indium, gallium and tin used as catalyst to convert CO2 back to carbon
An international team of scientists led by RMIT University in Melbourne, Australia claims to have discovered a technique to convert carbon dioxide (CO2) gas into solid carbon.
According to researchers, the new technique uses a liquid alloy to turn CO2 into carbon particles, thus providing an alternate pathway for removing the harmful greenhouse gas from our environment.
In recent years, scientists have had a limited success in finding metal catalysts that can convert CO2 into solid particles of carbon. But, a big problem with these catalysts is that they work only at very high temperatures - above 600°C.
Creating perfect working conditions for such catalysts therefore requires a lot of energy as well as money. Moreover, these catalysts have been observed to gum up quickly as the carbon builds up, thereby limiting their ability to keep the reaction going for longer times.
In the current study, the researchers focused on a new catalyst made from metal alloys, which are liquid at room temperature. The team created an alloy of indium, gallium and tin, which is able to conduct electricity and is liquid at room temperature.
The researchers smeared the alloy with a sprinkling of cerium and placed it inside a beaker. When they inserted a wire into the liquid metal, it resulted in a reaction between some of the cerium with oxygen from the air in the beaker, creating a thin layer of cerium oxide. However, most of the cerium in liquid metal remained protected.
Next, the researchers piped CO2 into the beaker and passed a small amount of electricity into the wire. They observed that CO2 slowly diffused into the liquid metal and converted into solid flakes of carbon. The flakes naturally detached from the surface of the liquid alloy, allowing non-stop production of solid carbon particles.
"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," said Dorna Esrafilzadeh, a chemist at RMIT University, and the lead author of the study paper.
"The process also produces synthetic fuel as a by-product, which could also have industrial applications," she added.
The detailed findings of the study are published in the journal Nature Communications.