TEM studies of the initial stage growth and morphologies of bamboo-shaped carbon nanotubes synthesized by CVD

摘要

The initial stage growth of bamboo-shaped carbon nanotubes (CNTs) synthesized by catalytic decomposition of methane is investigated. A special experimental procedure has been developed to stop the process after short durations (0 s to 3 min). It has found that during the early stages (60 s), carbon cluster-encapsulated nanoparticles are formed. With prolonging synthesis time (3 min), some CNTs coexisted with carbon cluster-encapsulated nanoparticles are formed. HRTEM observations show that these CNTs display multi-walled and bamboo structure and the encapsulated catalytic particles are quasi-cone morphologies. At the same time, the catalytic particles only encapsulated with carbon clusters present quasi-sphere structures. For growth up to 60 min, two kinds of bamboo mode structures are observed: conical, and cylindrical, which are developed by quasi-cone and quasi-spherc catalytic particles, respectively. Moreover, the early stage growth mode of the CNTs is predominantly of the base growth mode according to TEM observations.