Outerwall selective alkylcarboxylation and enrichment of double-walled carbon nanotubes

Abstract

Double-walled carbon nanotubes were enriched from their single- and few-walled counterparts as well as other carbonaceous byproducts coexisting in as-synthesized materials using Billups–Birch reductive alkylcarboxylation chemistry. The enrichment was made possible due to high selectivity of the reaction towards smaller diameter, single-walled carbon nanotubes and more defective carbonaceous structures. Raman resonant scattering studies suggest that alkylcarboxylation selectively occurred on the outerwalls while the inner-tubes remained unaffected. The separated double-walled carbon nanotubes were water soluble due to outerwall alkylcarboxylation, but the Raman modes and part of the optical properties of the inner-tubes were preserved.