Hydrogen storage on scandium-coated toroidal carbon nanostructure C ₁₂₀ modeled with density functional theory

Ab initio density functional calculations were performed on a toroidal carbon C₁₂₀ nanostructure doped from one to ten Sc atoms bonded to its outer surface. These calculations are based on DFT with the generalized gradient approximation PW91 (Perdew and Wang) as implemented in the Materials Studio v.4.3 code. The Dmol₃ module was used to calculate, among others, total energies, charge density, HOMO-LUMO and Mulliken population analysis. On the basis of these results, it is possible to propose that a single Sc atom is able to adsorb up to 6 H₂ molecules. Therefore the study was extended for a ystem with 10 Sc atoms, which can adsorb up to 60 H ₂ molecules. This leads to 6.01 wt %, which fulfils the current requirement (6 wt %, at 2010, specified by US Department of Energy (DOE)). Accordingly, the scandium-coated toroidal carbon C₁₂₀ nanostructure is a good candidate for H₂ storage with moderate adsorption energy.