SO2 structure and reactivity on clean and sulfur modified Pd(100)
1988; Elsevier BV; Volume: 194; Issue: 1-2 Linguagem: Inglês
10.1016/0039-6028(94)91257-2
ISSN1879-2758
Autores Tópico(s)ZnO doping and properties
ResumoBelow 120 K SO2 was found to adsorb intact on clean and sulfided Pd(100) surfaces. The molecule bonds to the surface via its sulfur atom with preferential occupation of a four-fold hollow binding site. The SO2 molecular plane apparently lies normal to the surface, but evidence of in-plane tilting and PdO binding was found, in sharp contrast to the out-of-plane tilt observed on Ag(110). This difference is explained in terms of the surface electronic structure of the two metals. Decomposition of SO2 on Pd(100) occurs above 240 K on the clean surface to yield adsorbed atomic oxygen and SO which in turn dissociates at higher temperatures. For initially high SO2 coverages an SO4 species is formed above 300 K by reaction of SO2 with oxygen formed in SO2 dissociation. A quarter monolayer of preadsorbed sulfur blocks SO2 decomposition, but the geometry and stability of adsorbed SO2 is not strongly perturbed at this sulfur coverage, suggesting that SO2 adsorbs in the four-fold hollow. At a sulfur coverage of 0.5 ML, adsorbed SO2 bonds weakly via the sulfur atom, and the molecule is no longer tilted. SO2 desorption is complete by 170 K at this sulfur coverage.
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