Chiral angle-dependent defect evolution in CVD-grown single-walled carbon nanotubes

Abstract

Defects are ubiquitous in nanomaterials and it is critical to understand and control defect densities in these materials for electronic, chemical, and mechanical applications. Until now the relationship between nanomaterial structure and defect density during synthesis was limited to theoretical studies with no experimental confirmation of the predictions. Here we study defect evolution during the synthesis of individual single-walled carbon nanotubes (SWCNTs) using in situ Raman spectroscopy. SWCNTs are an important class of nanomaterials, and offer the unique ability to study the effect of their chiral angle on defect evolution during growth – a widely explored theoretical area that still lacks experimental confirmation. Our data reveals the first experimental evidence of chiral angle dependence on the defect density in SWCNTs, with lower defect density for higher chiral angle SWCNTs despite their faster growth rate. Modeling of the kinetics of defect generation reveals formation energy as the critical factor driving steady-state defect densities, with higher formation energies for topological defects in higher chiral angle SWCNTs and lower energies for low chiral angle SWCNTs.