All the carbon nanotubes are fit to print

(Nanowerk News) Read all about this, carbon nanotube fans. Researchers at Rice and Swansea universities have developed a technique to use inexpensive newsprint harvested from newspapers to grow carbon nanotubes for industry.
A study (MDPI Journal C, "From Newspaper Substrate to Nanotubes – Analysis of Carbonized Soot Grown on Kaolin Sized Newsprint") initiated by late Rice researcher Robert Hauge and continued by research scientists Bruce Brinson and Varun Shenoy Gangoli and chemist Andrew Barron showed a particular kind of newsprint can be treated to serve as a three-dimensional substrate for single-walled carbon nanotube growth.
Single Walled Carbon Nanotubes Grown on Kaolin Sized Paper
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). (Image: Rice University) (click on image to enlarge)
“Stacked newsprint that incorporates kaolin clay and used as the catalyst-bearing substrate is a low- cost, very high surface-area growth medium compatible with continuous-flow production methods,” Brinson said.
Not all newsprint is created equal, since only that produced with kaolin (china clay) sizing allowed for carbon nanotube growth. Sizing is a filler incorporated into paper to change its absorption, color and wear characteristics. The researchers found that kaolin facilitates the reduction of iron to nanoscale catalyst particles that minimize the aggregation of nanotubes in the final product.
“Our observation that kaolin sizing, and not calcium carbonate sizing, offers insight into how the growth catalyst — in our case, iron — is affected by the chemical nature of the substrate,” said Barron, director of the Energy Safety Research Institute (ESRI) at Swansea.
One newspaper tested for nanotube growth, the Rice Thresher, was unsuitable, the researchers found. For those that worked, only the parts without ink served the purpose, limiting lab studies to sections trimmed from the papers’ edges.
Brinson estimated kaolin is part of 60% of the world’s paper products. “It’s whiter and brighter than most,” he said. “A key to newsprint is that it is thin, cheap and light. We only need the surface; the bulk between the front and back surfaces doesn’t count for much.”
The opportunity to prepare the substrate in bulk differentiates newsprint from traditional chemical vapor deposition substrates, Brinson said. He said the process promises to reduce the use of toxic materials and greenhouse gases in the bulk nanotube growth.
Source: By Mike Williams, Rice University
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