RAPID GROWTH OF CARBON NANOSTRUCTURES USING A MICROWAVE OVEN

Extremely fast growth of carbon nanotubes (CNTs), within just 5 sec, 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 (1800W) 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 [1]. Onion like carbon spheres (OLCSs) were also synthesized by heating a mixture of naphthalene and graphite powder inside a kitchen microwave oven for ~1 min under atmospheric conditions. Naphthalene, a hydrocarbon, provides carbon for growth, while graphite plays the crucial role of microwave absorber. Size of the OLCS particles was distributed over a wide range from few 10’s of nm upto a few µm. The OLCS particles self-assembled in long range chain-like structure. Addition of ferrocene as catalyst to the precursor mixture of naphthalene and graphite resulted in the formation of highly crystalline carbon encapsulated iron (in the form of oxide/carbide) nanoparticles with a core-shell structure [2].

References

[1] R. Bajpai and H. D. Wagner, Carbon, 2015, 82, 327-336.

[2] Reeti Bajpai, Lev Rapoport, Kobi Amsalem, Hanoch Daniel Wagner, under review CrystEngComm (manuscript ID: CE-ART-09-2015-001785)