Rice University chemists today revealed the first method for cutting carbon nanotubes into "seeds" and using those seeds to sprout new nanotubes. The findings offer hope that seeded growth may one day produce the large quantities of pure nanotubes needed for dozens of materials applications.
The research is available online and slated to appear in an upcoming issue of the Journal of the American Chemical Society.
Like vintners who hope to grow new vineyards from a handful of grape vine cuttings, Rice's chemists hope their new method of seeded growth for carbon nanotubes will allow them to reproduce their very best samples en masse.
"Carbon nanotubes come in lots of diameters and types, and our goal is to take a pure sample of just one type and duplicate it in large quantities," said corresponding author James Tour, director of Rice's Carbon Nanotechnology Laboratory (CNL). "We've shown that the concept can work."
The study's lead author, CNL founder and nanotube pioneer Richard Smalley, died in October 2005 after a long battle with leukemia. Tour said Smalley devoted an enormous amount of time and energy to the seeded-growth nanotube amplification research in the final two years of his life.
"Rick was intent on using nanotechnology to solve the world's energy problems, and he knew we needed to find a way to make large quantities of pure nanotubes of a particular type in order to re-wire power grids and make electrical energy widely available for future needs," Tour said. "Rick had a way of making things happen, and for six months during 2004, there were no fewer than 50 researchers in four Rice laboratories devoting their effort to this problem. It was unprecedented, and it paid off."
First discovered just 15 years ago, single-walled carbon nanotubes (SWNTs) are molecules of pure carbon with many unique properties. Smaller in diameter than a virus, nanotubes are about 100 times stronger than steel, weigh about one-sixth as much and are among the world's best electrical conductors and semi-conductors. Smalley, who devoted the last 10 years of his career to studying SWNTs, pioneered the first method for mass-producing them and many of the techniques scientists use to study them.
There are dozens of types of SWNTs, each with a characteristic atomic arrangement. These variations, though slight, can lead to drastically different properties: Some nanotubes are like metals, and others are semiconductors. While materials scientists are anxious to use SWNTs in everything from bacteria-sized computer chips to geostationary space elevators, most applications require pure compounds. Since all nanotube production methods, including the industrial-scale system Smalley invented in the 1990s, create a variety of 80-odd types, the challenge of making mass quantities of pure tubes – which Smalley referred to as "SWNT amplification" – is one of the major, unachieved goals of nanoscience.
"Rick envisioned a revolutionary system like PCR (polymerase chain reaction), where very small samples could be exponentially amplified," Tour said. "We're not there yet. Our demonstration involves single nanotubes, and our yields are still very low, but the amplified growth route is demonstrated."
The nanotube seeds are about 200 nanometers long and one nanometer wide – length-to-diameter dimensions roughly equal to a 16-foot garden house. After cutting, the seeds underwent a series of chemical modifications. Bits of iron were attached at each end, and a polymer wrapper was added that allowed the seeds to stick to a smooth piece of silicon oxide. After burning away the polymer and impurities, the seeds were placed inside a pressure-controlled furnace filled with ethylene gas. With the iron acting as a catalyst, the seeds grew spontaneously from both ends, growing to more than 30 times their initial length – imagine that 16-foot water hose growing by more than 500 feet – in just a few minutes.
Tour, Chao Professor of Chemistry, professor of mechanical engineering and materials science and professor of computer science, said CNL's team has yet to prove that the added growth has the same atomic architecture – known as chirality – of the seeds. However, he said the added growth had the same diameter as the original seed, which suggests that the methodology is successful.
Jade Boyd | EurekAlert!
When fat cells change their colour
28.10.2016 | Albert-Ludwigs-Universität Freiburg im Breisgau
Aquaculture: Clear Water Thanks to Cork
28.10.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH
Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.
So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
28.10.2016 | Power and Electrical Engineering
28.10.2016 | Physics and Astronomy
28.10.2016 | Life Sciences