Kinetic hindrance during the surface oxidation of Cu(100)–c(10×2)-Ag

Abstract

The influence of c(10x2)-Ag superstructure on the oxidation kinetics and oxygen adsorption-induced nanostructures on Cu(100) has been investigated as a function of O(2) exposure at 373 K by employing scanning tunneling microscopy and x-ray photoelectron spectroscopy. The oxygen adsorption-induced segregation of Cu through the Ag overlayer is found to trigger agglomeration of Ag and subsequent formation of ordered oval-shaped nanosize metallic Ag islands separated by Cu(100)-(2 radical2x radical2)R45 degrees -O surface phase. As oxygen exposure is further increased, all Ag is eventually covered by oxidized Cu. The presence of Ag delays the completion of the fully reconstructed (2 radical2x radical2)R45 degrees -O surface and the nucleation and growth of Cu(2)O islands by limiting Cu diffusion toward the surface. Once Cu(2)O grows into the bulk deeper than buried Ag, the oxidation kinetics follow that of the unalloyed clean Cu(100) surface. Similar kinds of Cu-O nanostructures are found on both clean Cu(100) and Cu(100)-c(10x2)-Ag surfaces. Details of the morphology of the Ag structures and kinetic control of the surface oxidation mechanism on Cu(100)-c(10x2)-Ag are discussed.

Atomistic simulations of copper oxidation and Cu/Cu2O interfaces using charge-optimized many-body potentials

“…Therefore, oxygen coverage on Cu (100) surface and the resulted reconstructions have been the subject of numerous theoretical and experimental studies. [64][65][66][67][68][69][70][71][72][73] With STM technique, different reconstructed Cu (100) surfaces which depend on the oxygen coverage are observed. 72,73 At oxygen coverage less than 0.3 monolayers (ML), the surface is characterized by micro-domains formed in a c(2x2) arrangement, which can be describe as oxygen atoms occupying the 4-fold hollow sites.…”

“…When the oxygen coverage rises above 0.5 ML, the missing-row reconstructed surface will be induced. 72,73 To study the interaction between oxygen molecules and the Cu surfaces with MD simulations, oxygen molecules are placed on Cu (100) surface, roughly 3Å ~ 5Å. The oxygen partial pressure is estimated around 100 oxygen atoms.…”

Fabrication of magnetically recyclable Ag/Cu@Fe3O4nanoparticles with excellent catalytic activity for p-nitrophenol reduction

“…It has been reported that when there is CuO on a surface, there is almost certainly Cu 2 O as well. [45][46][47][48] Therefore, although the XPS data further conrms the formation of metallic Cu and Ag, it can only be inferred that some of the Cu particles were oxidized during the preparation.…”

Surface segregation and stability of core–shell alloy catalysts for oxygen reduction in acid medium

“…Similar reconstruction phenomena have been observed on Ag/Cu systems under oxygen exposure. 61 The electrochemical potential shift (DU, in V) for the onset of Pt dissolution relative to that on the Pt(111) surface signals the relative stability of the Pt surface atoms (in vacuum and under O) for the reaction Pt -Pt +2 + 2e À in acid medium. 42 It is found that all the 3d-metals (Co, Ni, Cu) having significant size difference with Pt are unstable in the core, and tend to segregate to the surface.…”