Multi-component catalysts for the synthesis of SWCNT
We developed a large-scale synthesis of single-walled carbon nanotubes (SWCNT) based entirely on the electric arc evaporation method. To get the desired result, an enhanced understanding and control of the evaporation process is of crucial importance. For best results, one has to control the temperature gradient of the evaporation zone for a high evaporation density (challenging task) or alternatively one has to develop catalysts suitable for catalytic operation over a large temperature range. We found multi-component catalyst systems that allow both a low-temperature SWCNT growth (200 °C) as well as a high-temperature growth (1000 °C) and a lower SWCNT defect density. Multi-component catalysts, therefore, offered the best results for both the laser evaporation process with the arc process with a similar SWCNT yield. The evaporation rate, however, is much higher for the arc technique. This favours the arc technique over the laser technique for an upscaled SWCNT synthesis process.