Increase of Hydrogen Storage Capacity of CNTs by Using Transition Metal, Metal Oxide-CNT Nanocomposites

In this paper, we examined the synergetic effect of transition metals or their oxides as decorative agent with carbon nanotubes on the hydrogen storage capacity. The $TiO_2$, Pd, and PdO shell nanoparticles were used as decorative agent on the surface of carbon nanotubes. The samples were investigated by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The thermal stability was investigated by thermogravimetric analysis testing. The hydrogen storage capacity was measured by a custom-made Sieverts apparatus. The Pd and $TiO_2$ doped carbon nanotube shows the most marked hydrogen storage capacity, 7 times higher than pristin carbon nanotubes after 30 min storage. The results show that the hydrogen storage capacity of the PdO shell- carbon nanotube composite is very low in comparison with those of two others and does not represent a significant difference with that of carbon nanotubes.