GAMMA-RAY IRRADIATION-INDUCED IMPROVEMENT OF HYDROGEN ADSORPTION IN MULTI-WALLED CARBON NANOTUBES

An improved hydrogen adsorption capacity of 0.5-0.6 wt% was obtained at room temperature and 10.0 MPa pressure for commercial MWNT sample by gamma-ray irradiation, compared with 0.33 wt% of pristine MWNTs. The irradiation-induced defects in structure, which is favorable for hydrogen adsorption, were characterized by ESR spectrum, elemental analysis, and Raman spectrum. The results show that gamma-ray irradiation increased the hydrogen adsorption capacity due to the increasing number of defects created by gamma-photons, but would reach the maximum when defect concentration achieves saturation.