• Islam, M. S.
• Panigrahi, P.
• Ahuja, Rajeev
• Rao, G. S.
• Gupta, D.

Abstract

<p>Owing to its high energy density, the potential of hydrogen (H₂) as an energy carrier has been immense, however its storage remains a big obstacle and calls for an efficient storage medium. By means of density functional theory (DFT) in spin polarized generalized gradient approximation (GGA), we have investigated the structural, electronic and hydrogen storage properties of a light alkali metal (Li, Na) functionalized fluorographene monolayer (FG). Metal adatoms bind to the FG with significantly high binding energy, much higher than their cohesive energies, which helps to achieve a uniform distribution of metal adatoms on the monolayer and consequently ensure reversibility. Due to a difference of electronegativities, each metal adatom transfers a substantial amount of its charge to the FG monolayer and attains a partial positive state, which facilitates the adsorption of multiple H₂ molecules around the adatoms by electrostatic as well as van der Waals interactions. To get a better description of H₂ adsorption energies with metal-doped systems, we have also performed calculations using van der Waals corrections. For both the functionalized systems, the results indicate a reasonably high H₂ storage capacity with H₂ adsorption energies falling into the range for the practical applications.</p>

Topics

• density
• energy density
• theory
• Hydrogen
• density functional theory
• Alkali metal