Fast growth of carbon nanotubes using a microwave oven

Extremely fast growth of carbon nanotubes (CNTs), within just 5 s, was achieved by a facile microwave (MW) assisted heating technique, under ambient conditions. A mixture of graphite, ferrocene and carbon fiber was used as the precursor material. Growth characteristics were examined using different compositions of the precursor and MW powers. Both graphite and carbon fiber were found to be necessary for achieving fast growth of CNTs. MW heating of the precursor mixture at 100% power (1800 W) resulted in a yield of CNTs (26 ± 5 wt%). Conversion efficiency of carbon from ferrocene to CNT at 100% MW power is about 82 wt% on average. When relative proportion of graphite in the mixture is high, yield decreases but conversion efficiency of carbon increases. Base growth mode is proposed as dominant growth process of the CNTs. Driven by the capillary effect of CNTs, catalyst particles are found to be encapsulated inside the tubes at different locations along their length. Solvent free, instant, easy, and cost effective growth process proposed here using ordinary MW oven is likely to be amenable to scale-up for industrial production of CNTs.