Hydrogen Adsorption on Eu/SWCNT Systems: A DFT Study

Within the first-principles density functional theory, we investigate the interaction between H 2 and Eu-doped single-walled carbon nanotubes (SWCNT). For the Eu/SWCNT system, the hollow site on the outer wall of SWCNT is the most favorable for the adsorption. The charge analysis results show that two 6s electrons in Eu transfer to SWCNT while 4f electrons remain in Eu, and the Eu atom is thus divalent. The results indicate that five H 2 per Eu atom can be adsorbed in the Eu/SWCNT system while 4.44 wt % H 2 can be stored in the Eu 3 /SWCNT system. The interaction between H 2 and Eu/SWCNT is balanced by the electronic hybridization and electrostatic interactions.