DFT study of MoS2 and hydrogen adsorbed on the (10(1)over-bar0) face of MoS2

DFT calculations were employed to investigate the properties of the catalyt ically important (10(1) over bar 0) edge of MoS2 and the adsorption of hydr ogen thereon. The electronic properties of the bulk and surface as well as the relaxed positions of surface atoms are calculated by two different tech niques, namely all-electron and plane wave pseudo-potential DFT methods. Hy drogen adsorption is studied by means of a (2 x 1) surface cell to account for H-H interactions and the different configurations of adsorbed hydrogen atoms. Our calculations demonstrate that the electronic structure and the p ositions of the relaxed surface atoms obtained by the two methods are ident ical, with the exception of minor discrepancies which are attributed to the different relaxation procedures. The (10(1) over bar 0) surface of MoS2 co ntains weakly coupled S-S pairs formed by relaxation of its sulfur atoms. T he results of the hydrogen adsorption show that hydrogen is adsorbed on the sulfur pairs but not on Mo atoms on the surface. Only one of the possible configurations of adsorbed H atoms on a (2 x 1) cell is energetically favou red, while the energy of the other configurations is higher with respect to the energy of H-2 and MoS2.