Structural and Electrical Properties of Ozone Irradiated Carbon Nanotube Yarns and Sheets

Abstract

Poor electrical conductivity of carbon nanotube (CNT) yarn and sheets has been one of the main hurdles in their practical application. Here, we demonstrate that the ozone irradiation can be an effective approach to reduce the resistivity of spun CNTs bundle with oxidization and induced defects. The CNT yarn and sheet are fabricated from a spinnable vertically aligned CNT forest synthesized by a thermal chemical vapor deposition. The electrical resistance of a CNT yarn and sheet reduces with a certain period of ozone irradiation; however for a long duration of ozone irradiation resistance increases with structural deformation of the CNTs. A comparative study on the effect of shapes between the CNT yarn and sheet with morphological change in the CNTs due to the ozone irradiation is performed. It was observed that the desorption energy of ozone molecules was slightly large for the CNT yarn due to the difference of adsorption sites. The fraction of defects induced by the ozone irradiated on the CNT yarn was estimated from the ultimate resistance change with temperature and Raman spectroscopy.

Ni Nanobuffer Layer Provides Light-Weight CNT/Cu Fibers with Superior Robustness, Conductivity, and Ampacity

“…16 For CNT fiber, the electrical conductivity is usually 10 4 −10 5 S/m, 17 and various chemical modifications have been carried out to improve the conductivity, such as acid oxidation, 18,19 iodine doping, 20,21 auric/platinic acid treatment, 22 and ozone irradiation. 23 However, the improvement is still limited and the highest conductivity was 6.74 × 10 6 S/m, about 1 order of magnitude smaller than that of pure copper. 20 Furthermore, the Joule heating effect suppresses strongly the ampacity of CNT assemblies.…”

“…However, due to the weak van der Waals interaction , and remarkable electron and phonon scattering between CNTs, , there is a significant sacrifice of mechanical, electrical, and thermal properties when CNTs are assembled into macroscopic structures, such as one-dimensional fiber, , two-dimensional film, and three-dimensional bulk . For CNT fiber, the electrical conductivity is usually 10 4 –10 5 S/m, and various chemical modifications have been carried out to improve the conductivity, such as acid oxidation, , iodine doping, , auric/platinic acid treatment, and ozone irradiation . However, the improvement is still limited and the highest conductivity was 6.74 × 10 6 S/m, about 1 order of magnitude smaller than that of pure copper .…”

Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film

“…CNTs have several advantages compared to traditional filters, including chemical stability and resistance of high temperatures. Previous studies have proven that CNTs and CNT-coated films can filter particles and adsorb volatile organic vapors effectively. , As for interaction with ozone, several studies analyzed ozone adsorption on CNTs from microperspectives − and focused on electrical properties of ozonized CNTs. − However, one question yet to be addressed is how CNTs perform as filters for removing ozone? Furthermore, how do they compare with other ozone cleaners, such as AC and KI solutions?…”

Dry Functionalization and Doping of Single-Walled Carbon Nanotubes by Ozone

“…The decrease in the electrical conductivity beyond 30 min ozone exposure time might be attributed to the induction of large defects on the SWCNT walls and their fragmentation due to ozone etching, while the decrease of the sheet resistance up to 30 min of ozone exposure can be attributed to ozone adsorption and hole injection. 37,38 With initial exposure of SWCNTs to ozone, a physisorbed state may lead to the formation of primary ozonide. 39 This might contribute to the transduction mechanism of molecular adsorption, which happens through charge transfer, 40 and could be responsible for the increase in conductivity.…”