Influence of compressive strain on the hydrogen storage capabilities of graphene: a density functional theory study

Abstract

Pristine graphene is not suitable for hydrogen storage at ambient conditions since it binds the hydrogen molecules only by van der Waals interactions. However, the adsorption energy of the hydrogen molecules can be improved by doping or decorating metal atoms on the graphene monolayer. The doping and decoration processes are challenging due to the oxygen interference in hydrogen adsorption and the clustering issue of metal atoms. To improve the hydrogen adsorption energy in pristine graphene, we have explored the hydrogen storage capabilities of graphene monolayer in the presence of compressive strain. We found that at 6 % of biaxial compressive strain, a 4*4*1 supercell of graphene can adsorb 10 H2 molecules above the graphene surface. The average binding energy of H2 for this configuration is found to be -0.42 eV/H2, which is very suitable for reversible hydrogen adsorption. We propose that a 4*4*1 supercell of graphene can adsorb a total number of 20 H2 molecules leading to a high hydrogen uptake of 9.4 %. The interaction between orbitals of carbon and hydrogen atoms and 2 the charge transfer process have been studied by plotting the partial density of states and surface charge density plots. The electronic density around the C-C bonds of graphene increases in the presence of compressive strain, due to which hydrogen molecules are strongly adsorbed.

An ab initio study of catechol sensing in pristine and transition metal decorated γ-graphyne

“…Hence, the bond distance is inversely proportional to the binding energy. Moreover, sp hybridized carbon atoms are more electronegative compared to sp 2 hybridized bonds due to the more contribution of s orbital; hence, more charge accumulation will take place on sp bonds [46,69]. Thus, the Ti atom is strongly adsorbed with acetylene carbon rings, resulting in high binding energy.…”

Potential reversible hydrogen storage in Li-decorated carbon allotrope PAI-Graphene: A first-principles study

“…2D carbon nanomaterials are proven to be promising hosts since they possess relatively lower molecular mass, large surface area, and hydrogen can be adsorbed to the front as well as to the backside of nanomaterials. Pristine carbon nanostructures bind hydrogen molecules only through van der Waals interactions and, therefore, they are inefficient for reversible hydrogen storage applications under ambient conditions [55,56,57]. The binding of hydrogen molecules improves when nanostructures are decorated with metal atoms since strong electrostatic and Kubas interactions [58] also play a vital role in hydrogen adsorption to these structures.…”