Synthesis of Bulk Amount of Double-Walled Carbon Nanotubes

65201 Carbon nanotubes of uniform structure and properties are highly promising new materials for energy production, storage devices, and many other applications. A new type of carbon nanotube with two tubular layers (double-wall carbon nanotube, DWNT) shows improved physical properties over previous nanotube structures; however, an efficient method to selectively produce this unique carbon nanotube structure is needed. This project will develop an understanding of the mechanism of DWNT production, leading to optimum methods for maximizing production and material quality. In Phase I, DWNT production was optimized in an arc-based reactor. In addition, a chemical vapor deposition (CVD) DWNT reactor was constructed and successfully demonstrated. Purified DWNT samples, with controlled diameters from 1.3 to 6 nm, were prepared and shown to have excellent field emission properties. Phase II will scale up the arc reach and develop a continuous CVD reactor for high production rate, high purity DWNT products. The purification process will be further developed to improve throughput, and a comparison of various DWNT types will be made. Commercial Applications and Other Benefits as described by the awardee: DWNTs have been demonstrated to be more conductive and more resistant to thermal decomposition compared to multi- or single-wall carbon nanotubes. DWNTs should have application as electron field emitters and as atomic force microscope probe tips. Since DWNTs have superior electrical conductivity, they are excellent candidates as connectors in nanocircuitry and MEMS tech-nology. Additional applications include gas storage (i.e. hydrogen) and fuel cell and battery electrodes.