Adsorption and reaction of hydrogen sulfide on thin-film cerium oxide

The adsorption and reaction of hydrogen sulfide, H2S, have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The behavior of the H2S was examined as a function of Ce oxidation state. H2S weakly chemisorbs on fully oxidized CeO2 desorbing near 155 K. Hydrogen from the H2S reacts with the surface O to desorb as water between 200 K and 450 K. When ca. 20% of the Ce4+ is reduced to Ce3+ more H2S dissociates to -OH and -SH and water is produced near 580 K. When the ceria is ca. 70% reduced, water formation is suppressed and H2 desorbs near 580 K. S 2p photoelectron spectroscopy indicates the decomposition of H2S into -SH and then -S as the sample is annealed from 100 K to 600 K. O 1s photoemission indicated the presence of H2O and -OH.