Microstructure evolution of predefined catalysts for diameter-controlled growth of single-walled carbon nanotubes

Predefined catalysts have been recently successfully employed for diameter- and chirality-selective CVD growth of single-walled carbon nanotubes (SWCNTs).^[1-3] They simplify the exhausting optimization of parameters for in situ catalyst formation and ensure a very good control of catalyst properties. Using C:Ni nanocomposite templates (NCTs) as catalyst precursors, SWCNTs with a selective, monomodal diameter distribution were obtained. More than the half of the SWCNTs had a diameter of (1.36±0.10) nm.^[3]

While the preparation of NCTs is well defined and controlled, the activation of the NPs for nanotube synthesis by CVD is a critical step that is still not fully understood. Element-resolved scanning and high-resolution transmission electron microscopy and Raman spectroscopy were used to clarify the microstructure of C:Ni NCTs in the different stages of the SWCNT growth. These studies reveal a distinct change of the NCT microstructure by conserving the initial nanocomposite morphology to a very large extend.

[1] F. Yang et al., Nature 510, 522 (2014);
[2] H. An et al., Nanoscale 8, 14523 (2016);
[3] S. Melkhanova et al., Nanoscale 8, 14888 (2016)