CNT growth from C:Ni nanocomposites

Precise control of single walled carbon nanotube (SWCNT) diameter, chirality, alignment, and intertube arrangement are still remaining challenges in the catalytic chemical vapour deposition (CCVD) synthesis. In this context it has still to be clarified whether a predefined size and shape of the nanoparticles can be stabilized by a suitable matrix material while preserving the catalytic activity of the metal.
For this study Ni nanoparticles were encapsulated in an amorphous carbon matrix by physical vapour deposition. As prepared Ni catalysts were used for CNT fabrication by laser assisted CVD applying either no external carbon source or C₂H₄ gas, and by low pressure CVD applying C₂H₂ or CH₄ as carbon source. The broad range of CNT synthesis conditions indicates the robustness of the embedded Ni particles as a catalyst for carbon nanotube formation. SEM and laser wavelength dependent Raman spectroscopy were used for CNT characterisation. The nickel-SWCNT-interaction was modelled by density functional calculations with the projector augmented plane wave method, utilizing the generalized gradient approximation for the exchange-correlation functional.