Sc-Decorated WS2 Nanoribbons as Hydrogen Storage Media**Supported by the National Natural Science Foundation of China under Grant No 11404112, the Research in Cutting-Edge Technologies of Zhengzhou under Grant No 141PRKXF622, and the Foundation of Henan Educational Committee under Grant No 14B140020.

Abstract

The hydrogen storage behavior of Sc-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 Sc-decorated 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 mechanism and the Coulomb attraction make the Sc atoms stably adsorb on the edges of WS2 nanoribbons without clustering. The 2Sc/WS2 NRs system can adsorb at most eight H2 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.