A kind of conical cup-stacked carbon nanotube

In this article, a kind of conical cup-stacked carbon nanotubes (CSCNTs) grown by the microwave irradiation of the mixture of ferrocene and carbon black nanoparticles is reported. They are characterized by the long-cone shape, the nearly unchanged wall thickness and the huge hollow core. SEM and TEM analyses reveal that they are formed by the stacking of the truncated conical graphene layers precipitated from the surfaces of catalysts. The motions and coalescences of catalysts result in the increase of catalyst size during reaction. At the same time, the inner diameter of the truncated conical graphite layer precipitated from the surface of catalyst can increase with the catalyst size continuously. As a result, the as-grown CSCNTs have the conical hollow core and almost unchanged wall thickness. To the best of our knowledge, this kind of conical CSCNTs has been reported for the first time.