The extraordinary electronic and optical properties of single walled carbon nanotubes (SWNTs) are determined by their structure; SWNTs are1 either metallic or semiconducting depending on their diameter and chirality . Many valuable applications in, for example, transparent conductors, solar cells, biosensors and nanoelectronics, require nanotubes of specific electronic character and puritiy2. Current techniques for the separation of SWNTs into semiconducting and metallic species are only partially successful due to the difficulty in the dispersion of SWNTs3 and separation occurs only on a limited scale. Here, using technology exclusively licensed from University College London Business (UCLB)*, we detail a fully scalable method of SWNT purification and separation based on the different susceptibilities of impurities, metallic SWNTs and semiconducting SWNTs to chemical reduction. Transferral of these reduced tubes as a dry powder to an organic solvent allows for the spontaneous dissolution of the most easily reduced fraction. By carefully controlling the metal to carbon ratio in the initial liquid ammonia reduction the spontaneously dissolved fraction can be tailored to contain predominantly metallic SWNTs, predominantly carbonanous impurities or a representative sample of the raw SWNTs. Hence, using this method, powders of purified SWNTs and semiconducting SWNTs along with powders or solutions of metallic SWNTs and raw SWNT can be easily, quickly and scalably produced.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2011: Advanced Materials, CNTs, Particles, Films and Composites
Published: June 13, 2011
Pages: 163 - 166
Industry sector: Advanced Materials & Manufacturing
Topics: Carbon Nano Structures & Devices