Facile flame catalytic growth of carbon nanomaterials on the surface of carbon nanotubes

Hierarchical carbon structures with in-situ growth of small carbon particles on thick CNT (TCNT) were synthesized by a simple flame synthesis method. TEM tomography analysis indicated that flame synthesized CNT (FCNT) with different length and diameter (or carbon sphere particles) were deposited onto both the inner and/or outer tubular wall surface of the TCNT. The nano-confinement effect of the TCNT tubular space on the flame growth of carbon particles was investigated, which led to the formation of shorter and curved FCNT. Electron microscopy studies revealed that the tip growth mechanism dominated the ethanol flame-induced CNT synthesis process and the rate determining step for the flame growth of CNT was the nickel-catalyzed carbon deposit reaction rather than the mass transfer of the carbon source in the confined nano-channels of the TCNT. The influence of the type of metal catalyst on the products was also studied. Substantial improvements of electrochemical properties of TCNT after the decoration with FCNT confirmed the effectiveness and advantages of this method. The FCNT/TCNT anodes delivered a higher reversible lithium ion storage specific capacity than that of the pristine TCNT.