Hydrogen storage in carbon nanotubes modified by microwave plasma etching and Pd decoration

Microwave plasma etching and Pd decoration methods were employed for the modification of carbon nanotubes (CNTs). The defects on the nanotube wall increased after the etching process as determined from HRTEM observation and Raman measurement. The defects supplied more hydrogen accesses to the interlayers and hollow interiors of CNTs. The results of hydrogen uptake measurements showed that the etched CNTs had higher hydrogen storage capability than that of the original sample at ambient temperature and pressure of 10.728 MPa. Furthermore, the CNTs decorated with Pd showed a hydrogen storage capability of 4.5 wt.%, about three times higher than that of the non-decorated samples. The hydrogen uptake mechanism of the modified CNTs was discussed.