Alkali-metal-induced enhancement of hydrogen adsorption in C₆₀ fullerene: an ab initio study

Abstract

It is demonstrated that the doping of alkali metal atoms on fullerene, C₆₀, remarkably enhances the molecular hydrogen adsorption capacity of fullerenes, which is higher than that of conventionally known other fullerene complexes. This effect is observed to be more pronounced for sodium than lithium atom. The formation of stable complex forms of a sodium-doped fullerene molecule, Na₈C₆₀, and the corresponding hydrogenated species, [Na(H₂)₆]₈C₆₀, with 48 hydrogen molecules has been demonstrated to lead to a hydrogen adsorption density of ~9.5 wt %. One of the main factors favoring the interactions involved is attributed to the pronounced charge transfer from the sodium atom to the C₆₀ molecule and electrostatic interaction between the ion and the dihydrogen. The suitability of these complexes for developing fullerene-based hydrogen storage materials is discussed.