Hydrogen storage in carbon nanotubes

Several hydrogen adsorption and stored geometries on carbon nanotubes are i dentified by density-functional calculations. Hydrogens can be stored in an arch type or zigzag type up to coverage 1.0, and stored inside capillary w ith higher coverage. The C-H bond formation changes the electronic structur es of metallic carbon nanotubes to semiconductors. It suggest that doping o r additional conductive materials to the nanotube electrode is required in electrochemical hydrogen storage process.