Effects of proton irradiation on thermal stability of single-walled carbon nanotubes mat

We report effects of proton irradiation on thermal oxidation of single-walled carbon nanotubes (SWNTs). Following 400 keV proton irradiation to doses of 1013–1017 cm−2, thermal oxidation of SWNTs was conducted at temperatures 200–700 °C. The mass of SWNTs during oxidation was monitored with thermogravimetric analysis (TGA) and ion-beam-induced structural modifications in nanotubes were characterized with Raman spectroscopy. Proton irradiation leads to enhanced thermal stability of nanotubes, as indicated by increased values of the temperature (Tmax) for maximum oxidation rate, e.g. Tmax ∼ 495 °C for pristine SWNTs and Tmax ∼ 525 °C for SWNTs irradiated to the dose of 1 × 1015 cm−2. The activation energy for oxidation increases gradually from 1.13 ± 0.01 eV for pristine SWNTs, to ∼1.25 ± 0.02 eV for the largest dose of 5 × 1016 cm−2. Based on the correlation between TGA and Raman data, we discuss possible mechanisms for the observed effects of proton irradiation on SWNT thermal oxidation.