Li-decorated carbon ene–yne as a potential high-capacity hydrogen storage medium

Abstract

Based on comprehensive first-principles calculations, we predict that Li-decorated carbon ene–yne (CEY) can serve as a reversible and high density hydrogen storage medium. The adsorption structures, charge transfer, electronic properties and energy storage characteristics of Li-decorated CEY are investigated. It is established that Li can bind strongly to sp and sp² hybridized CEY without the formation of Li clusters. The strong interaction between Li and CEY is attributed to the sp binding C p_x/p_y states which hybridize heavily with the Li 2s/2p states. After Li decoration, CEY undergoes a transition from a semiconductor to a metal. Each Li atom anchors seven H₂ molecules with the average adsorption energy falling in a suitable range (−0.2 to −0.4 eV per H₂). The adsorption mechanism of H₂ molecules has also been discussed. Two Li atom decorated CEY can obtain up to a 9.96 wt% hydrogen storage capacity.