A first principles study of hydrogen storage on lithium decorated two dimensional carbon allotropes

• Published in: International journal of hydrogen energy Vol. 40; no. 18; pp. 6128 - 6136
• Main Authors: Yadav, Shwetank, Tam, Jasmine, Singh, Chandra Veer
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 18.05.2015
• Subjects: Carbon allotropes; Density functional theory; Graphyne; Hydrogen storage; Physisorption; Graphyne; Density functional theory; Hydrogen storage; Carbon allotropes; Physisorption
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2015.03.038

Graphene has been intensively investigated as a possible hydrogen storage medium due to the spectacular properties granted by its two-dimensional nature. Since graphene's discovery, several new two-dimensional carbon allotropes have been theorized and synthesized. We investigated the hydrogen storage ability of six such allotropes: C65, C64, C63, C62, C31 and C41. The ability to anchor lithium metal atoms over each allotrope and the hydrogen binding energies for each lithium decorated allotrope were studied with density functional theory using LDA, GGA and vdW-DF2 (for describing van der Waals interactions) functionals. All the allotropes were able to achieve double sided lithium decoration and hydrogen adsorption. Every allotrope other than C31 possesed lithium binding energies stronger than bulk lithium's cohesive energy which indicates that adsorbed lithium atoms will not cluster on the allotrope surface. Furthermore, every structure produced hydrogen binding energies stronger than that of lithium decorated graphene, suggesting the potential of use of these structures in practical hydrogen storage media. The C41 structure was able to adsorb far more hydrogen molecules than any other structure with a maximum hydrogen gravimetric density of 7.12 wt.% using the vdW-DF2 functional. [Display omitted] •Two-dimensional carbon allotropes studied for hydrogen storage with DFT.•Lithium decorated hydrogen adsorption looked at with LDA, GGA and vdW-DF2.•Each structure produced stronger hydrogen binding energy than graphene.•C41 structure can yield upto 7.1 wt. % hydrogen gravimetric density.