Single wall carbon nanotubes for conductive wiring

The scarcity of ore and environmental intensity of copper production creates a strong incentive to explore alternative materials for conducting electricity. Single-walled carbon nanotubes (SWCNT) rely on plentiful feedstock materials (i.e., graphite) and exhibit high theoretical conductivity on a per mass basis. However, bulk conductivities measured at the laboratory scale indicate further improvements in carbon nanotube ribbons and wires are necessary to create a competitive alternative. This paper investigates methods for improving the conductivity of SWCNT ribbons and wires. As-produced SWCNT material was synthesized from pulsed laser vaporization of doped graphite targets. The resulting as-produced material was purified in excess of 95%, based on optical absorption spectroscopy, and fabricated into free-standing buckypapers without the aid of polymer or binders. Nearly an order of magnitude increase in conductivity was achieved for mechanical densification of SWCNT wires. Chemical doping of SWCNT papers with nitric acid resulted in an increase in electrical conductivity from 2.7x10⁴ S/m to 1x10⁶ S/m.