Experimental and theoretical study of oxygen adsorption structures on Ag(111)

TL;DR

This study combines experimental and theoretical approaches to explore various oxygen adsorption structures on Ag(111), revealing complex surface behaviors that influence catalytic oxidation processes.

Contribution

It provides a comprehensive analysis of diverse oxygen structures on Ag(111), including newly observed phases and detailed atomic geometries, advancing understanding of oxidation catalysis.

Findings

Multiple stable oxygen structures identified on Ag(111) surface.

Discovery of a new c(4 x 8) oxygen overlayer structure.

Complex co-existence of various oxygen phases impacts catalytic understanding.

Abstract

The oxidized Ag(111) surface has been studied by a combination of experimental and theoretical methods, scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). A large variety of different surface structures is found, depending on the detailed preparation conditions. The observed structures fall into four classes: (a) individually chemisorbed atomic oxygen atoms, (b) three different oxygen overlayer structures, including the well-known p(4 x 4) phase, formed from the same Ag$_6$ and Ag$_{10}$ building blocks, (c) a c(4 x 8) structure not previously observed, and (d) at higher oxygen coverages structures characterized by stripes along the high-symmetry directions of the Ag(111) substrate. Our analysis provides a detailed explanation of the atomic-scale geometry of the Ag$_6$/Ag$_{10}$ building block structures, and the c(4 x 8) and stripe structures are discussed in detail. The observation of many different and co-existing structures implies that the O/Ag(111) system is characterized by a significantly larger degree of complexity than previously anticipated, and this will impact our understanding of oxidation catalysis processes on Ag catalysts.