Ruthenium decorated single walled carbon nanotube for molecular hydrogen storage: A first-principle study

Abstract

Molecular hydrogen storage on Ruthenium (Ru) decorated single-walled carbon nanotube (SWCNT) has been studied by using spin-polarized density functional theory (DFT). When a Ru atom is adsorbed on SWCNT, the Bader analysis reveals that Ru transfers a charge of 0.44e to SWCNT. Accordingly, Ru acts as adsorption center for H2 molecules; thus, it can hold up to four H2 molecules with an adsorption energy (Eads) of 0.93 eV/H2. A uniform addition of Ru atoms on SWCNT shows that this nanomaterial can adsorb up to five Ru without clustering. Each Ru atom of 5Ru-decorated SWCNT system can bind up to four H2 molecules involving an Eads of 0.83 eV/H2. After H2 molecules adsorption, Ru atoms shifted from a near hollow site to a bridge site. Moreover, Ru-decorated systems reduce their magnetic moment when the number of H2 molecules increase from 2 mB to 0 mB.