Scientists turn carbon dioxide into ultra-strong nanofibers
In an effort to mitigate man-made climate warming, scientists are focusing on ways to remove carbon dioxide from the atmosphere. One of the new ways to do this was announced by scientists from Brookhaven National Laboratory (BNL) and Columbia University (CU).

Carbon dioxide (CO2) is a potent greenhouse gas, meaning it has the ability to absorb heat and warm the planet. Although carbon dioxide is a natural part of the Earth's atmosphere, human activities have accelerated its emissions and are estimated to account for 79% of all greenhouse gas emissions attributed to human activities.

So scientists are trying to find ways to remove it from the atmosphere in the hope that this will help slow or even reverse the dangerous trend of climate warming.

Now researchers have announced one of the most creative approaches to removing CO2   from the air. It involves using both electrochemical and thermochemical reactions at relatively low temperatures to convert harmful gas into useful carbon nanofibers.

"If you divide the reaction into several steps, you can consider using different types of energy inputs and catalysts to make each part of the reaction work," said the study's lead author Zhenhua Xie.
The researchers first used an electrocatalyst made of palladium supported on carbon, which, when an electric current was applied, split a mixture of CO2 and water into carbon monoxide (CO) and hydrogen (H2).
They then turned to an iron-cobalt alloy thermal catalyst. This allowed them to convert first-stage CO into carbon nanofibers at just 400°C, which they say is a much more achievable heat level for industrial-scale use.

“By combining electrocatalysis and thermal catalysis, we use this tandem process to achieve something that neither process alone could achieve,” said CU's Jingguang Chen, who led the study.

Moreover, as the carbon nanofibers formed, they pushed the catalyst away from the surface, allowing it to be captured and reused. In terms of reuse, the researchers also say that the hydrogen produced in the first stage can be further captured and reused as a fuel source.

“For practical applications, both factors are really important – the analysis of CO2 emissions and the recyclability of the catalyst. Our technical results and other analyzes indicate that this tandem strategy opens the door to decarbonizing CO2  into valuable solid carbon products while producing renewable H2.”

Because carbon nanofibers are so strong, the researchers say they could have many applications, particularly as a concrete strengthener.

“You can put carbon nanofibers in cement to strengthen the cement,” Jingguang Chen said. “This will lock the carbon in the concrete for at least 50 years, and potentially longer. By then, the world should shift first to renewable energy sources that do not emit carbon dioxide.”
The study was published in the journal Nature Catalysis.