Carbon nanotubes, one of the strongest and lightest materials known to man, are regarded as one of the world’s greatest supermaterials. But despite constantly bombarding the news with newly discovered applications or breaking new world records, carbon nanotubes are still not taking over the world.
It has been nearly three decades since Thomas C. Maganas and Alan L. Harrington discovered carbon nanotubes in 1991. Yet 27 years later and carbon nanotubes have barely made any impact on an industrial level. The reason is simple, carbon nanotubes are ridiculously expensive to manufacture.
However, Ph.D. student Anna Douglas and their team have proposed a new solution to the costly problem.
Turning the Air into Cheap Carbon Nanotubes
In a recent paper published in ACS publications, the team of scientists from Vanderbilt University outlined a new method of extracting cheap carbon nanotubes from CO₂ molecules in the air.
According to the paper, the cost of the energy consumption was far lower than the value of the carbon nanotubes manufactured. While no specifics were mentioned about how much cheaper, the research could finally make the large-scale production of carbon nanotubes a very near possibility.
“Our research advance demonstrates a pathway to synthesize carbon nanotubes better in quality than these materials with lower cost and using carbon dioxide captured from the air.”
“The cheapest carbon nanotubes on the market cost around $100-200 (USD) per kilogram,” Douglas said. “Our research advance demonstrates a pathway to synthesize carbon nanotubes better in quality than these materials with lower cost and using carbon dioxide captured from the air.”
With this new method, the process of turning carbon dioxide into carbon nanotubes at a profit is perhaps economically viable. Soon, companies will be able to convert carbon dioxide gas into various carbon nanotube products and sell them at a profit - perhaps the most environmentally sound business model to date.
“What we’ve learned is the science that opens the door to now build some of the most valuable materials in our world, such as diamonds and single-walled carbon nanotubes, from carbon dioxide that we capture from air through our process,” Pint said.
How the Process Works
The exact mechanism of how carbon nanotubes form is still not fully understood. However, the new process involves a rather uncommon method of nanotube production - electrochemistry.
The method produces cheap nanotubes with remarkably small diameters, a process which often requires incredible precision and sophisticated machinery. Although, the new process requires rather primitive equipment.
Instead of using complex machines to assemble small sections of carbon nanotubes, the new research explores a much simpler approach. The method involves layering a thin film of iron on top of a sheet of aluminum. When placed within a salt solution and induced by an electric current, the iron acts as a catalyst to start the formation of carbon nanotubes structures on the surface on the steel plate.
In this picture, electricity passes through an iron-coated steel plate, causing carbon nanotubes to begin forming on the surface of the plate.
“One of the most exciting things about what we’ve done is use electrochemistry to pull apart carbon dioxide into elemental constituents of carbon and oxygen and stitch together, with nanometer precision, those carbon atoms into new forms of matter,” said Assistant Professor Cary Pint. “That opens the door to being able to generate really valuable products with carbon nanotubes. These could revolutionize the world.”
Although the research is groundbreaking, researchers continue to struggle with manufacturing carbon nanotubes strands only a few centimeters long.
To date, the largest carbon nanotube ever produced measures just under half a meter long - far off from the 100,000 km tether required to build a space elevator.
The news is exciting and will certainly expedite the implementation of carbon nanotubes in everyday life. However, it will be many years and likely much longer until everything is understood about manufacturing cheap carbon nanotubes.