First-principles studies of H_2S adsorption and dissociation on metal surfaces

摘要

Density functional theory calculations were employed to investigate the molecular and dissociative adsorption of H_2S on the closed packed surfaces of a number of important noble metals (Ag(111), Au(111) and Cu(111)) and transition metals (Ir(111), Ni(111), Pd(111) and Pt(111)). Energy minima corresponding to adsorbed states were identified with H_2S binding preferentially at the top sites. The adsorption of other S moieties (SH and S) was also examined. SH and S were found to prefer bridge sites and hollow sites, respectively. The binding of H_2S and its S-containing dissociated species is stronger on the transition metals. The elementary reactions of abstraction of H from H_2S to form a surface SH intermediate and abstraction of H from SH to form a surface S intermediate as model pathways for the dissociation of H_2S were examined. Our results suggest that H_2S decomposition on the aforementioned transition metal surfaces is more facile, both thermodynamically and kinetically.