Chemisorption of H 2 and H 2S on the (100) surface of RuS 2: an ab initio theoretical study

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The chemisorption of H 2 and H 2S molecules on the (100) surface of RuS 2 is studied with a periodic Hartree-Fock approach completed by density functional correlation energy corrections. The stable (100) surface is modeled by a slab for which both molecular and dissociative chemisorptions are considered. For H 2, as well as for H 2S, the best optimized situations are for the molecular adsorptions, even if dissociated forms are found to be more favorable than the free gas molecules. The H 2 molecule is chemisorbed on the surface Ru atom in an η 2 lateral coordination with a strongly weakened HH bond, whereas the H 2S molecule is interacting by the S lone pairs with the Ru completing around it the bulk-like environment. The electronic structures for both molecular and dissociated optima are discussed in terms of orbital analysis with the help of projected density-of-states and crystal orbitals overlap populations. The crucial role of the S 2 pairs at the surface on the chemisorption properties is underlined.