Ru-decorated single walled carbon nanotube as a potencial hydrogen storage material

VALERIA VERDINELLI; ESTEFANIA GERMAN; ALFREDO JUAN; MARIA ALICIA VOLPE

Gothenburg

Conferencia; 28th International Conference on Diamond and Carbon Materials; 2017

Elsevier

Since Dillon et al. reported that carbon nanotubes (CNTs) can be used to store considerable amounts of hydrogen; several researchers have examined their H2 adsorption properties. In spite of favorable reports, pristine carbon nanostructures present, in some cases, a maximum H2 adsorption of 1 wt% at room temperature. Decorating CNTs with transition metals (TMs) such as ruthenium is a promising strategy for enhancing hydrogen adsorption.Hydrogen adsorption on Ru-decorated (8,0) single walled carbon nanotubes (SWCNT) was studied using spin polarized density functional theory calculations taking into account van der Waals interactions. Adatoms adsorption energies were calculated considering four possible sites on CNT surface. It was found that Ru atom prefers to be adsorbed near the hollow site, involving a favorable energy. The influence of Ru decoration on H2 adsorption behavior was analyzed in detail. It can be observed that hydrogen adsorption inside and outside the CNT improves when Ru decorated system is compared to pristine CNT. The electronic structures and changes in the chemical bonding for Ru and H2 on CNT were computed by density of states (DOS) and work function (WF) methods, concluding that 5pz and 4dz2 orbitals play an important role in H2 adsorption process, as well as, it can be noticed that WF increases and the band gap energy decreases in comparison with bare CNT. Moreover, Ru-decorated CNT systems exhibit magnetic properties. Bader´s analysis reveals that Ru acts as electron donor whereas H atoms act as electron acceptors. Thus, we can conclude that Ru-decorated (8,0) SWCNT is an appropriate and very potential candidate for hydrogen storage applications.