Hydrogen storage on lithium decorated zeolite templated carbon, DFT study

Abstract

Zeolite templated carbon (ZTC) nanostructure has generated significant interest due to its extremely large surfaces and surprisingly uniform micro-pores, for high hydrogen storage capacity. In the present work, we report calculations on decorating the ZTC carbon nano-structure convex surface with Lithium atoms, in order to be able to use this decorated system as hydrogen storage medium. Calculations for a ZTC nano-structure decorated with one and up to three Lithium atoms attached to its convex surface are made. This calculations are based on density functional theory (DFT), using the generalized gradient approximation PW91 (from Perdew and Wang), in Dmol3 of Materials Studio. Dmol3 used to calculate the total energies, energies of highest and lowest occupied molecular orbitals (HOMO and LUMO) and Mulliken population analysis. Based on these calculations, when Lithium atoms are adsorbed on a convex surface of nanostructure ZTC each Lithium atom can adsorb six molecules of H2, corresponding to a gravimetric storage capacity hydrogen 6.78 weight percent (wt%). This is in line with the gravimetric target for mobile hydrogen storage systems, which is 4.5–6.5 wt%, established by the Department of Energy (DOE) of the United States of America. The results show that forming the nanostructure ZTC system decorated with Lithium atoms (LiC39H9), a good candidate as medium for storing hydrogen is obtained.