A fast, efficient and reversible approach to enhance the electrical conductivity of carbon nanotube films†

Abstract

The modification of carbon nanotube (CNT) films is of great significance for improving their performance and expanding their applications. Halogen doping is found to be an effective way to enhance the electrical conductivity of CNT materials; however, the process either requires a harsh environment or time-consuming and tedious operations. In this study, we report a fast processing approach to efficiently enhance the electrical properties of CNT films. Based on a simple electrolytic process, halogens (Cl and Br) are doped into CNT films, inducing electron transfer from CNTs to halogens due to the high electronegativity of halogens. We employ XPS and Raman spectroscopy to confirm the occurrence of halogen (Cl and Br) dopants and the electron transfer phenomenon in the system. We emphasize that this approach allows us to complete the doping process in 90–180 seconds. Cl doping and Br doping increase the electrical conductivity of CNT films by nearly 21 and 20 times, with the values enhanced from 1.31 × 10⁴ S m⁻¹ to 2.73 × 10⁵ S m⁻¹ and to 2.62 × 10⁵ S m⁻¹, respectively. Moreover, the recycling results of doping and annealing show that this approach is revisable, which offers great potential in the emerging nanotechnology fields, such as energy storage, high-sensitivity sensors and electromagnetic interference shielding.