SO₂ Surface Chemistry on Metal Substrates

Abstract

The surface chemistry, induced by thermal and non-thermal methods, of S02 on metal substrates is reviewed. The substrate temperature during dosing is important; regardless of metal, adsorption is dissociative at 300 K and molecular at 100 K. On Ni, Pd, and Pt, molecular adsorption occurs through the S and one o atom, and the molecular plane is perpendicular to the surface. However, on Ag and Cu, adsorption occurs only through the S with the molecular plane perpendicular to the surface. The differences can be attributed to the structure of the metal's molecular orbitals and their interactions with the S02 orbitals. Upon heating, 50 2 dissociates on all transition metal surfaces with the exception of Ag, Au, and Cu, where only molecular desorption occurs. On Pt, Fe, and Pd, additional reactions are observed between S02 and its dissociation 'prodacts. The nonthermal reactions induced by photons and electrons for monolayer coverages of S02 on Ag(lll) are dominated by molecular desorption. Desorption cross sections for 313 TInt photons and 50 eV electrons were 2_8 x 10-20 em? and -I x 10-16 cm 2, respectively. Nonthermal excitation mechanisms and quenching processes as well asinteresting characteristics of 50 2 under irradiation are also reviewed. 433

Adsorption and Reaction of SO2 on Graphene-Supported Pt Nanoclusters

“…A thorough understanding of sulfur surface chemistry is therefore of great commercial and environmental interest. In general, atomic sulfur and its oxides, SO x (x = 1-4) exhibit a rich surface chemistry on noble metals [23][24][25][26]. A number of different adsorption states has been reported for SO x and the wide range of possible oxidation states leads to several feasible reaction pathways [27][28][29][30][31][32][33][34][35].…”