Adsorption and dissociation of H_2S on Mo(100) surface by first-principles study

摘要

Density-functional theory calculations had been used to investigate the adsorption and dissociation of H_2S on Mo(100) surface. Adsorption mechanisms of H_2S, HS, S and H on the Mo(100) surface were analyzed. H_2S was found to be adsorbed at bridge, hollow and top sites with adsorption energies of -1.25, -1.03 and -0.92 eV, respectively. HS was strongly chemically absorbed at hollow, bridge and top sites with adsorption energies of -4.51, -4.08 and -3.45 eV, respectively, and sulfur and hydrogen preferred to be absorbed at hollow and bridge sites, respectively. In addition, potential energy profiles of H_2S dissociation on Mo(10 0) had been constructed by a climbing image nudged elastic band method. Four possible dissociation pathways of the first H_2S dehydrogenation were examined with reaction barriers of 0.28,0.37,0.075, and 0.21 eV, respectively, while the energy barrier to break the S-H bond of HS with or without hydrogen co-adsorption was almost the same low. This work showed that the decomposition of H_2S on the molybdenum surface was kinetically and thermodynamically facile. Local densities of electronic states were further used to characterize the interaction between H_2S and substrate.