Microscope images of single walled carbon nanotubes: on the left, produced by the original Rice University HiPco method; on the right, produced by the new NoPo HiPco method. Image: Energy Safety Research Institute, Swansea University.A new method for producing high-quality carbon nanotubes – tiny molecules with incredible physical properties used in touchscreen displays, 5G networks and flexible electronics – has been given the green light by researchers, meaning work in this crucial field can continue.
Single-walled carbon nanotubes (SWCNTs) are among the most attractive nanomaterials for a wide range of applications, from nanoelectronics to medical sensors. They can be viewed as being like a single graphene sheet rolled into a tube. Their properties vary widely with their diameter, their chirality – how symmetrical they are – and how the graphene sheet is rolled up.
The problem faced by researchers is that it is no longer possible to make high-quality research samples of SWCNTs using the standard method. This was associated with the Carbon Center at Rice University, which used the high-pressure carbon monoxide (HiPco) gas-phase process developed by Nobel Laureate, the late Rick Smalley.
The demise of the Carbon Center in the mid-2010s, the divesting of the remaining HiPco samples to a third-party entity with no definite plans for further production and the expiration of the core patents for the HiPco process meant that this existing source of nanotubes was no longer an option.
Now, however, a collaboration between scientists at Swansea University in the UK, Rice University, Lamar University and NoPo Nanotechnologies in India has demonstrated that the latter's process and material design is a suitable replacement for the Rice method. The scientists report their findings in a paper in C — Journal of Carbon Research.
Analysis of the Rice ‘standard’ and the new commercial-scale samples show that back-to-back comparisons are possible, with the newer HiPco nanotubes from NoPo Nanotechnologies comparing very favorably to the older ones from Rice. These findings will go some way to reassuring researchers who might have been concerned that their work could not continue, as high-quality nanotubes would no longer be readily available.
"Variability in carbon nanotube sources is known to be a significant issue when trying to compare research results from various groups," said Andrew Barron of Swansea University's Energy Safety Research Institute and the project lead. "What is worse is that being able to correlate high-quality literature results with scaled processes is still difficult."
Erstwhile members of the Smalley group at Rice University, which developed the original HiPco process, helped start NoPo Nanotechnologies, with the aim of updating the HiPco process and producing what they call NoPo HiPCO SWCNTs.
"It is in the interest of all researchers to understand how the presently available product compares to historically available Rice materials that have been the subject of a great range of academic studies, and also to those searching for a commercial replacement to continue research and development in this field," said lead author Varun Shenoy Gangoli from Rice University.
This story is adapted from material from Swansea University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.