Hydrogen Adsorption on TM-decorated (8,0) SWCNT: A DFT Study

VALERIA VERDINELLI; ESTEFANÍA GERMÁN; CARLA ROMINA LUNA; ALFREDO JUAN

Berlin

Workshop; Hands-on workshop density-functional theory and beyond: First-principles simulations of molecules and materials.; 2015

Fritz Haber Institute

Hydrogen based energy sources is one of the promising solution to environmental pollution. Nevertheless, one of the major drawbacks is to find new materials capable of storing hydrogen in large per mass at a low cost. Single walled carbon nanotubes (SWCNTs) have many potential advantages for hydrogen adsorption over currently available adsorbents. However, SWCNTs do not adsorb considerable amount of hydrogen at normal conditions. Experimental and theoretical studies have showed that CNT turn more active for hydrogen adsorption at ambient conditions when CNT are doped with transition metal atoms (TM). In this work, we studied the hydrogen adsorption on (8,0) single walled carbon nanotubes decorated by Ru and Rh atoms. Spin polarized functional theory calculations with van der Waals corrections were performed using VASP code. Several decoration sites on the CNT surface were investigated before atomic or molecular hydrogen adsorption. We also included a systematic study on the electronic and bonding properties of the different systems by means of Density of states (DOS) and overlap population density of states (OPDOS) calculation. TM decoration increases hydrogen atom adsorption energy compare to pristine CNT. When a hydrogen molecule is considered on Ru/SWCNT its adsorption is dissociative with an Eads(H2) = -0.70 eV while H2 adsorption on Rh/SW CNT has an Eads(H2) = -0.99 eV . Furthermore, TM-decorated SWCNT systems exhibit magnetic properties. According to our results, TM decorated zig-zag nanotubes are great candidates for hydrogen storage applications.