Sulphur-induced structural chemistry of oxide surfaces

Christopher A. Muryn, Douglas Purdie, Peter Hardman, Allen L. Johnson, N. S. Prakash, Ganesh N. Raiker, Geoffrey Thornton, Daniel S.L. Law

Research output: Contribution to journalArticlepeer-review

Abstract

Surface EXAFS, NEXAFS and photoemission have been used to study the structure of surface phases resulting from reaction of H2S with NiO(100) and SO2 with TiO2(110). S K-edge SEXAFS data, in conjunction with the LEED pattern symmetry, suggest that the NiO(100)/H2S reaction at 570 K results in reduction of the substrate to form an azimuthally aligned Ni(100)c(2 × 2)S raft, with S occupying the fourfold Ni(100) hollow site. S K-edge NEXAFS results for SO2 adsorption on low-temperature TiO2(110) identify two surface SOx species: chemisorbed SO2 and SO2-4. The polarisation dependence of the NEXAFS suggests that the SO2 molecular plane lies close to parallel to the surface. Photoemission data also evidence chemisorption at 110 K and show that this precursor phase reacts further in a thermally activated process to form a stable surface sulphate-like species. A mechanism is suggested which involves SO2 bonding to a terrace Ti site, with an activated hop to an adjacent site in which sulphur bonds to two oxygen atoms on the raised row.

Original languageEnglish
Pages (from-to)77-89
Number of pages13
JournalFaraday Discussions of the Chemical Society
Volume89
DOIs
Publication statusPublished - 1990

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