Effect of steam-treatment time on the length and structure of single-walled and double-walled carbon nanotubes

A major challenge to turn the potential of carbon nanotubes (CNTs) into customer applications is to reduce or eliminate their toxicity. Taking into account health and safety concerns, intensified research efforts have been conducted to improve the biocompatibility of CNTs, including the development of new shortening and purification strategies. Ideally, the methods used for improving the biocompatibility of CNTs should not alter the electronic properties of CNTs. Herein, we report on the shortening of a sample containing single-walled and double-walled CNTs using steam and obtain new insights in the properties of the steam-treated CNTs. The present study shows that short CNTs (median length ca. 200 nm) can be obtained under the reported conditions. Raman analysis reveals that wider and outer nanotubes undergo more significant changes than the narrower and inner ones, especially after a prolonged steam treatment