Ab initio study on hydrogen interaction with calcium decorated silicon carbide nanotube

Ab initio study on the viability of calcium decorated silicon carbide nanotube as a hydrogen storage material was conducted. Calcium strongly adsorbs on silicon carbide nanotube (SiCNT) with a significant binding energy of −2.83 eV, thus calcium's low cohesive energy and strong binding with SiCNT may prevent Ca to form clusters with other adsorbates. Bader charge analysis also revealed a charge transfer of 1.45e from Ca to SiCNT resulting to calcium's cationic state, which may induce charge polarization to a nearby molecule such as hydrogen. Hydrogen molecule was then allowed to interact with the calcium adatom where it exhibited charge polarization, induced by the electric field from calcium's positive charge. This resulted to a significant binding energy of −0.22 eV for the first hydrogen molecule. Results reveal that Ca on SiCNT can hold up to 7 hydrogen molecules and can be a promising candidate for a hydrogen storage material.