Growing carbon nanotubes on newspaper
Image: Researchers reveal that newspapers made with Kaolin filler make an effective substrate for carbon nanotube growth. [Brinson et al. Journal of Carbon Research]
Researchers at Rice University, US, and the Energy Safety Research Institute at Swansea University, UK, have discovered that carbon nanotubes can be grown on some newspapers via carbon vapour deposition, at scale.
Transmission electron microscopy, Raman spectroscopy, scanning electron microscope and energy dispersive X-ray spectroscopy revealed that the large surface area of newspaper acts as an effective substrate for single-walled carbon nanotube growth, but only when the newspaper is produced from a kaolin clay filler.
As researcher Varun Shenoy Gangoli from Chemistry at Rice University says: "Many substances including talc, calcium carbonate, and titanium dioxide can be used in sizing in papers which act as a filler to help with their levels of absorption and wear.”
“However it was our observation that kaolin sizing, and not calcium carbonate sizing, showed us how the growth catalyst, which in our case was iron, is affected by the chemical nature of the substrate," he explains.
Large-scale nanotube production is hindered by the high cost of preparing a suitable surface for chemical growth as well as difficulties in scaling the process, as only single surface growth processes have been previously available.
However, the latest study details the research experiments carried out in producing carbon nanotubes which could have the potential to solve some of the problems associated with large scale production.
Kaolin newsprint was impregnated with nanoparticle precursors and calcined for 30 min at 400°C.
The resulting char residue was loaded into a carbon vapour deposition chamber and used as a substrate for SWCNT growth at 750 °C.
The research team discovered that the large surface area of newspapers provided an unlikely but ideal way to chemically grow carbon nanotubes.
TEM images of raw carbon soot grown on kaolin sized paper showing (a) roped single-walled carbon nanotubes (SWCNTs) helically wrapped by a SWCNT, and large SWCNTs, (b) collapsed, (c) folded, and (d) twisted nanotubes. Scale bar = 10 nm (a–c) and 50 nm (d). [Brinson et al. Journal of Carbon Research]
As lead researcher Bruce Brinson, Rice, says: "Newspapers have the benefit of being used in a roll-to-roll process in a stacked form making it an ideal candidate as a low-cost stackable 2D surface to grow carbon nanotubes."
However, only newspaper produced with a kaolin sizer resulted in carbon nanotube growth.
As the researchers report in Journal of Carbon Research, experiments using the newspaper substrates produced with kaolin filler resulted in hybridized sp2–sp3 bonded carbon species. The soot was found to consist primarily of carbon nanotubes and graphene nanoribbons.
"While there has been previous research that shows that graphene, carbon nanotubes and carbon dots can be synthesised on a variety of materials, such as food waste, vegetation waste, animal, bird or insect waste and chemically grown on natural materials, to date, this research has been limited,” says ESRI Director, Professor Andrew Barron.
"With our new research, we have found a continuous flow system that dramatically reduces the cost of both substrate and post synthesis process which could impact on the future mass manufacture of single walled carbon nanotubes," he adds.
Research is published in Journal of Carbon Research.