On the nature of the SO42-/Ag(111) and SO42-/Au(111) surface bonding

E. M. PATRITO; P. PAREDES OLIVERA; HARRELL SELLERS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 1997 vol. 380 p. 264 - 264

he nature of sulfate-Ag(lll) and sulfate-Au(lll) surface bonding has been investigated at the SCF+MP2 level of theory. Convergence of binding energy with cluster size is investigated and, unlike neutral adsorbates, large clusters are required in order to obtain reliable binding energies. In the most stable adsorption mode, sulfate binds to the surface via three oxygen atoms tC3vsymmetry) with a binding energy of 159.3 kcal/mol on Ag(111) and 143.9 kcal/mol on Au(lll). The geometry of adsorbed sulfate was optimized at the SCF level. While the bond length between sulfur and the oxygens coordinated to the surface increases, the sulfur uncoordinated oxygen bond length decreases. This weakening and strengthening of the bonds, respectively, is consistent withbond order conservation in adsorbates on metal surfaces. Although a charge transfer of 0.4 electrons towards the metal is observed, the adsorbate remains very much sulfate-like. The molecular orbital analysis indicates that there is als