Enhanced adsorption of Xe and Kr on boron doped graphene sheet decorated with transition metals (Fe, Ni, Cu and Zn)
Abstract
Efficient adsorption and segregation of Xe & Kr gases is of high importance in commercial as well as nuclear industries. Systematic ab initio calculations reveal that transition metal (TM) decorated boron doped graphene (BDG-TM) sheet can act as an efficient substrate for adsorptive capture of Xe & Kr (adatoms). Substantial enhancement in the adsorption energy (Eads) is obtained on BDG-TM substrates and it varies as BDG-Cu > BDG-Ni > BDG-Fe > BDG-Zn. The improvement is approximately four times of the pristine BDG and twice that of the conventional metallic substrates. Badar charge analysis and charge density difference maps envisage that, the TM decoration alters the charge distribution at substrate-adatom interface, which in turn brings a considerable change in the polarization of adatom, leads to significant improvement in the Eads. The change in polarization of adatoms is interlinked with charge transfer process and it has been gauged by computing their effective charges upon adsorption; which follows the same sequence of Eads and hence corroborated each other. Later, the partial density of states analysis shows a splitting and strong hybridization of Xe-p with TM-d orbitals near the Fermi level of Fe, Ni and Cu decorated systems, unveils a strong adsorption. Further, the effect of clustering and dispersion of Cu atoms on Eads are analyzed using a first principle based genetic algorithm, which reveals that clustering of Cu atoms deteriorate the Eads of Xe & Kr. Thus for experimental realization, BDG sheet with uniformly dispersed fine Cu particles is proposed as a substrate.