Purifying carbon nanotube wires by vacuum annealing

We propose vacuum annealing to purify carbon nanotube wires (CNTWs) manufactured from surfactant dispersions by removing residual carbonaceous impurities (surfactant and solvent) included during wire-spinning. We analysed the CNTW purity post-annealing vs. treatment temperature and time by scanning electron microscopy, Raman spectroscopy, and thermogravimetry. Our results suggest that maximal purification is achieved after annealing at 800 °C (for ≥3 h) or at 1000 °C (for ≥1 h). The optimally purified wires show higher CNT content and G/D (∼93 wt% and >30, respectively) than the untreated wires (∼71 wt% and 25, respectively).