Structural Inhibition of Silver Surface Oxidation

Abstract

Surface structure and oxidation are key to silver-based heterogeneous catalysis. Prevention of surface reconstruction may favor electrophilic oxygen, which is believed to be the active species in silver-catalyzed oxidation. To determine whether terrace width or step geometry enables control of oxidation and concomitant reconstruction, we investigated oxidation of the topmost layer of a curved Ag(111) crystal. This crystal contains a range of terrace widths having either A- or B-type step geometries. Atomic oxygen was used to facilitate oxidation, temperature-programmed desorption quantified the extent of oxygen adsorption, and scanning tunneling microscopy characterized the formation of reconstructed areas. While A-type steps prove to have little influence, B-type steps hinder reconstruction. We attribute the difference to geometric-dependent growth mechanisms of silver oxide surface reconstructions.

RAIRS Characterization of CO and O Coadsorption on Cu(111)

“…Dissociative adsorption on Cu(111) and vicinals occurs preferentially on step edges and kink defects. ,, Small defect islands rapidly oxidize to form triangular islands that grow with O 2 exposure. A very similar oxidation mechanism was shown to occur on silver using a c -Ag­(1 1̅1)[110] R 31° crystal. , Our current RAIRS results indicate that the remaining nonoxidized Cu(111) patches after partial oxidation of the surface are electronically unperturbed, because the center of the CO band frequency does not change. We only find that the clean Cu(111) area decreases with increasing O 2 exposure.…”

“…A very similar oxidation mechanism was shown to occur on silver using a c -Ag(1 1̅1)[110] R 31° crystal. 58 , 59 Our current RAIRS results indicate that the remaining nonoxidized Cu(111) patches after partial oxidation of the surface are electronically unperturbed, because the center of the CO band frequency does not change. We only find that the clean Cu(111) area decreases with increasing O 2 exposure.…”

Adsorption dynamics of O2 on Cu(111): a supersonic molecular beam study

“…Ag(111). 34,35 The growth of the oxide patches reduces remaining clean Cu(111) surface area that binds post-dosed CO. The CO is otherwise unaffected as evidenced from the exact same internal stretch frequency.…”

Monolayer-interface-driven strain-free heteroepitaxy for single-crystal Ag thin films

“…The elemental pro les of Ag and O across the surface, obtained from energy dispersive X-ray spectroscopy (EDX) analysis (Fig. 1f), suggested that the chemical purity of Ag was well preserved up to the topmost surface layer of the at Ag lm and did not exhibit surface oxidation 27 .…”