Influence of catalyst metal particles on the hydrogen sorption of single-walled carbon nanotube materials

The hydrogen sorption capacity of arc-synthesized single-walled carbon nanotubes (SWNTs) was studied using a specially built high-pressure rig coupled to a Toepler pump capable of directly measuring the desorbed volumes of gas. The samples studied were prepared using the arc-evaporation method and were as-produced SWNT material formed at the cathode (collar), as-produced SWNTs deposited in the soot and a purified sample of SWNTs. The three samples had similar diameter ranges, the major difference between them being the concentration of remaining metal particles from the Ni/Y/C catalyst used in the arc-synthesis. The effect of the presence of these residual catalyst metal particles has been analysed and seen to strongly influence the hydrogen storage capacity of the samples.