First Principles Study of Hydrogen Storage on Ru-Doped (8,0) Single-Walled Carbon Nanotube

VALERIA VERDINELLI, ESTEFANÍA GERMÁN, JORGE M. MARCHETTI, MARÍA A. VOLPE, ALFREDO JUAN

Madrid

Conferencia; NANOSTRUC 2014: International Conference on Structural Nano Composites; 2014

NANOSTRUC

Hydrogen is considered an alternative fuel because its use creates neither air pollution nor greenhouse gas emissions. However, it exhibits two important drawbacks in its applications: production costs and storage characteristics. Due to their well known fascinating properties, carbon nanotubes seem to be a convenient material to viable hydrogen storage systems. Several studies demonstrated that hydrogen adsorption ability onto the single-walled carbon nanotubes (SWCNTs) can be enhanced by transition metals doping into the side wall. In this work, hydrogen adsorption onto Ru decorated (8,0) zigzag SWCNT was studied. Spin-polarized density functional theory (DFT) simulations were performed using VASP code. Four possible decoration sites on the nanotube surface (i.e., the H site above the hexagon, the Z and A sites above zigzag and axial C-C bonds and the T site above the carbon atom) were investigated before atomic hydrogen adsorption; being the most stable location for a single Ru atom at H site, with a binding energy of Eb=-2.20 eV. It was found that H adsorption is energetically more favorable on Ru/SWCNT (Eads= -2.29 eV) than that on bare SWCNT (Eads~-0.9 eV). It was also observed that H-Ru distance increases when compared with H-Ru molecule by 5% while C-Ru distance increases by 3% for H-Ru/SWCNT system, which presents magnetic effects. It can be concluded that H interaction is stronger on magnetic systems.