Enriching the hydrogen storage capacity of carbon nanotube doped with polylithiated molecules

In a quest to find optimum materials for efficient storage of clean energy, we have performed first principles calculations to study the structural and energy storage properties of one-dimensional carbon nanotubes (CNTs) functionalized with polylithiated molecules (PLMs). Van der Waals corrected calculations disclosed that various PLMs like CLi, CLi2, CLi3, OLi, OLi2, OLi3, bind strongly to CNTs even at high doping concentrations ensuring a uniform distribution of dopants without forming clusters. Bader charge analysis reveals that each Li in all the PLMs attains a partial positive charge and transform into Li+ cations. This situation allows multiple H-2 molecules adsorbed with each Li+ through the polarization of incident H-2 molecules via electrostatic and van der Waals type of interaction. With a maximum doping concentration, that is 3CLi(2)/3CLi(3) and 3OLi(2)/3OLi(3) a maximum of 36 H-2 molecules could be adsorbed that corresponds to a reasonably high H-2 storage capacity with the adsorption energies in the range of -0.33 to -0.15 eV/H-2. This suits the ambient condition applications. (C) 2018 Elsevier B.V. All rights reserved.