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

摘要

We report effects of proton irradiation on thermal oxidation of single-walled carbon nanotubes (SWNTs). Following 400 keV proton irradiation to doses of 10~(13)-10~(17) cm~(-2), thermal oxidation of SWNTs was conducted at temperatures 200-700℃. 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 (T_(max)) for maximum oxidation rate, e.g. T_(max) ～ 495℃ for pristine SWNTs and T_(max) ～525℃ for SWNTs irradiated to the dose of 1 x 10~(15) 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 x 10~(16) 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.