Role of single walled carbon nanotube in nanophase MgH₂ hydrogen storage system

While the hydrogen storage property of bulk MgH₂ is remarkable, the nanophase MgH₂ is not completely understood. Wu et al. experimentally investigated the hydrogen storage properties of MgH ₂/single walled carbon nanotube composite systems and found that, while all the carbon additives acted as effective composite phase, Single-walled carbon nanotubes exhibited the most prominent catalytic function to enhance the hydrogen storage properties of MgH₂. We wish to confirm this role of single walled carbon nanotube in MgH₂/single walled carbon nanotube using first principles calculation. We functionalized single walled carbon nanotube with MgH₂ and hydrogenated. It is found that one can get a hydrogen storage capacity of 5.0-6.4 wt % with the hydrogen binding energy around 0.3 eV, in this carbon nanotube-8MgH₂ complex. Our study confirms that the carbon nanotubes neither act as catalysts nor as a component of the composite phase.