Sc-Decorated WS2 Nanoribbons as Hydrogen Storage Media1

The hydrogen storage behavior of So-decorated WS2 monolayer and WS2 nanoribbons is systematically studied by using first principles calculations based on the density functional theory. The present results indicate that an Sedecorated WS2 monolayer is not suitable for storing hydrogen due to the weak interaction between the monolayer WS2 sheet and the Sc atoms. It is found that both the hybridization meeh~nism and the Coulomb attraction make the Sc atoms stably adsorb on the edges of WS2 nanoribbons without clustering. The 2Sc/WS2NRs system can adsorb at most eight H.2 molecules with average adsorption energy of 0.20 eV/H2. The results show that the desorption of H2 is possible by lowering the pressure or by increasing the temperature.