DFT study of hydrogen adsorption on Eu‐decorated single‐ and double‐sided graphene

Abstract

We carry out density functional theory calculations to study the adsorption of hydrogen molecules on Eu‐decorated single‐ and double‐sided graphene sheets. It is found that Eu prefers to adsorb on the hollow site of carbon ring above both the single‐ and double‐sided graphene. The hybridization of Eu on graphene is mainly between the Eu‐5d orbital and the C‐2p orbital. The charge of Eu is enhanced when the first hydrogen molecule approaches the Eu atom. As more hydrogen molecules are introduced, the charge population of Eu‐5d and 6p orbital is increased. Each Eu can stably bind up to six hydrogen molecules with an average adsorption energy of −0.404 and −0.392 eV for Eu decorated single‐ and double‐sided graphene, respectively. Eu atoms carry negative charge when 12 hydrogen molecules are attracted by the Eu‐decorated double‐sided graphene. The main interaction between hydrogen and Eu is similar to Kubas binding, which contains hybridization of H–σ* and Eu‐5d orbital and charge transfer between them.