Adsorption and dissociation of H2S on Rh(100) surface by First-principle study

The adsorption and dissociation of H2S on Rh(100) surface have been investigated using self-consistent periodic density functional theory. The adsorption mechanisms on Rh(100) surface of H2S, HS, H and S were examined. It is found that H2S is weakly adsorbed on bridge, top and hollow sites with their adsorption energies of −0.98, −0.86 and −0.82 eV, respectively. In contrast to H2S, HS is strongly chemisorbed on Rh(100) surface at hollow, top and bridge site with the adsorption energies of −4.33, −4.31 and −3.85 eV, whereas S and H preferred to be absorbed at hollow site. By using climbing nudged elastic band method (CI-NEB), we found the four most feasible paths for H2S dissociation on Rh(100), with energy barriers of 0.19 eV, 0.25 eV, 44 meV and 98 meV, respectively. The energy barrier to break the S-H bond of HS with H co-adsorption or without H co-adsorption was almost the same low. This study reveals that H2S decomposition on Rh(100) surface is a facile process both kinetically and thermodynamically.