WASHINGTON — Researchers have built the world’s first carbon nanotube complex capable of conducting electricity, raising hopes for material that might someday be used in electrical cables and wireless devices.
“We have shown how to lay a fiber,” said Daniel Nocera, lead author of the study published Wednesday in Nature Communications.
A team at the Omicron Lab at Washington University in St. Louis worked with colleagues from the U.S. Department of Energy’s Oak Ridge National Laboratory, Ontario College of Applied Arts and Science in Canada and Drexel University in Philadelphia to reproduce and lay an aluminum foil covering over aluminum nanotubes, a promising material that can be used for everything from solar panels to flight and communication towers.
The aluminum foil remains transparent, but not nearly as small and transparent as ordinary filaments. Omicron researchers tried to break down its insulating properties and to treat it to make it conduct electrical current.
“It was a challenge to get the aluminum to lay itself uniformly into wires at the nanoscale,” said Jeremy Lewis, who co-led the Oak Ridge lab with Nocera.
The Oak Ridge lab worked with conventional, compressed air to conduct electricity through the aluminum foil. But as the aluminum atoms moved as they were propelled inside the carbon nanotube, the aluminum atoms moved in slightly opposite directions. Lewis and other researchers said that a helium boost was needed to ensure the aluminum didn’t drag air around the structure instead of passing through it.
“That’s what I saw in the lab, which was a straight line,” Lewis said.
Nocera said the firing-line was powered by a 100-watt solar cell and used as a standard 10-kilowatt laboratory setup. The group said the material does perform better than usual plastic wrappers with other conductors. But a study by co-author Sun Yu, an Oak Ridge scientist, said the team doesn’t know what its conductivity will be like in electronic and wireless devices.
What they do know is that they can build complex nanotubes now — and create them more quickly — and that the aluminum foil method adds several nanometers to the thickness of the nanotubes and decreases their width.
“This really allows us to build our (nanotube) nanostructures in less time,” Lewis said.
He said the lab will continue to produce small sheets of the aluminum nanotubes.
“Now that we have demonstrated it can be done, we can potentially use this technique to improve our existing structures and, of course, we can also switch to different conductors,” Lewis said.
Nocera said he hopes the technology could eventually increase efficiency of existing wires and become less expensive.
“From a cost perspective, there is a jump from the transparent foil we used to make to the invisibility cloak stuff that you have,” Nocera said. “The amount of space and time it takes to get to a material this thin — imagine a device that was this thin — it costs you a lot of energy to get to that material.”
“If it makes our own materials, it will be significantly more efficient than what’s out there,” he said.