Adsorption and reaction of H2S on Cu(110) studied using scanning tunneling microscopy

Abstract

Using low-temperature scanning tunneling microscopy (STM), the adsorption and reaction of hydrogen sulfide (H₂S) and its fragments (SH and S) on Cu(110) are investigated at 5 K. H₂S adsorbs molecularly on the surface on top of a Cu atom. With voltage pulses of STM, it is possible to induce sequential dehydrogenation of H₂S to SH and S. We found two kinds of adsorption structures of SH. The short-bridge site is the most stable site for SH, while the long-bridge site is the second. Density functional theory calculations show that the S–H axis is inclined from the surface normal for both species. The reaction of H₂S with OH and O was directly observed to yield SH and S, respectively, providing a molecular-level insight into catalyst poisoning.