Preparation of short and water-dispersible carbon nanotubes by solid-state cutting

A new approach is reported to cut conventionally long (>10 μm) and entangled carbon nanotubes (CNTs) to those with short lengths (∼300 nm) and excellent dispersion in water and ethanol. This was achieved by depositing Fe2O3 nanoparticles on CNTs first and then inducing a chemical reaction between them at a temperature of 850 °C. The consumption of carbon during the reduction of Fe2O3 with CNTs was responsible for the cutting. Fourier transform infrared, X-ray photoelectron and Raman spectroscopies demonstrated that the cutting had induced little impact on the intrinsic graphitic structure. The present cutting approach based on the localized reaction in solid-state has advantages of producing short CNTs with a narrow length distribution, high dispersion, and a low material loss over previous ones based on gaseous or liquid-state reactions, and would have wide applications.