NEC Corp. says it has discovered a nano carbon material, the "carbon nanobrush" a fibrous aggregate of single-walled carbon nanohorns, that it says will improve the electrical conductivity and functioning of an array of materials and devices.

Carbon nanohorns are horn-shaped nano carbon structures 2-5 nanometers (nm) in diameter and 40-50nm in length. Until recently they have been produced as radial spherical aggregates. The carbon nanobrush is composed of radially assembled, graphene-based, single-walled nanotubules whose structure resembles that of a round brush.

(Left) Tips of single-walled carbon nanohorns, and (right) spherical-carbon nanohorn aggregates. Image credit: NEC Corp."The 'carbon nanobrush' is a new nano carbon material that, like existing carbon nanohorns, has high water and solvent dispersity, and high adsorptivity, including substance adsorption, but has more than 10 times the electrical conductivity [of] existing carbon nanohorns, an important characteristic for industrial applications," says Dr. Sumio Iijima, senior research fellow at NEC.

The carbon nanobrush may help to improve the basic functionality of a range of devices, including increasing the speed of sensor and actuator responses, improving the output properties of batteries and capacitors, while increasing the electrical conductivity of rubber and plastic composite materials, as well as having application in a wide range of industries.

As with spherical carbon nanohorns, the carbon nanobrush can contain various substances in the nano-sized spaces inside its tubular structure, so it can be used as a high-performance adsorbent. The inner space can be used when holes are formed on the surface of the carbon nanohorns by oxidation treatments, expanding the surface area by a factor of approximately five and greatly increasing adsorptivity.

NEC says the carbon nanobrush can be produced at room temperature and under atmospheric pressure using the laser ablation method, in which an iron-containing carbon target is irradiated by a laser with high power density. This production process means that it can be produced efficiently and at low cost compared to that of other nano carbon materials, the company says.