Carbon Nanotube to Gas Atoms Interaction Precisely Measured

Interaction occurring between atoms and molecules that constitute air, and the carbon surface used in battery electrodes and air filters has been measured at the most precise level yet by University of Washington physicists. The resulting data could be key information for improving technologies including batteries, electrodes and air filters.

The team used a carbon nanotube as a transistor to study what happens when gas atoms come into contact with the nanotube’s surface. Carbon nanotubes are seamless, hollow graphite structure a million times thinner than a drinking straw

Team leader David Cobden, UW professor of physics, said the researchers found that when an atom or molecule sticks to the nanotube, a tiny portion of the charge of one electron is transferred to its surface. A measurable change in electrical resistance results:

“This aspect of atoms interacting with surfaces has never been detected unambiguously before. When many atoms are stuck to the miniscule tube at the same time, the measurements reveal their collective dances, including big fluctuations that occur on warming analogous to the boiling of water.

Various forms of carbon, including nanotubes, are considered for hydrogen or other fuel storage because they have a huge internal surface area for the fuel molecules to stick to. However, these technological situations are extremely complex and difficult to do precise, clear-cut measurements on.”

Lithium batteries are concerned with lithium atoms sticking and transferring charges to carbon electrodes. In activated charcoal filters, molecules stick to the carbon surface to be removed.

The findings, Cobden said, are the most precise and controlled measurements of these interactions ever made, and will allow scientists to learn new things about the interplay of atoms and molecules with a carbon surface.

Reference:

Boris Dzyubenko, Hao-Chun Lee, Oscar E. Vilches & David H. Cobden
Surface electron perturbations and the collective behaviour of atoms adsorbed on a cylinder
Nature Physics 11, 398–402 doi:10.1038/nphys3302

Illustration: atoms sticking to a carbon nanotube, affecting the electrons in its surface. Credit: David Cobden and students at the University of Washington

Carbon Nanotube to Gas Atoms Interaction Precisely Measured