Unveiling the origin of oxygen atomic impurities in Au nanowires

Abstract

The appearance of unusually large Au-Au bond distances in linear atomic chains (LACs) of Au nanowires is commonly attributed to the presence of atomic impurities. However, the origin of those contaminants is unknown. We present a study based on density functional theory calculations using quasistatic (T=0) and finite-temperature ab initio molecular-dynamics simulations of a possible route for the formation of atomic impurities in Au nanowires. This process starts with the adsorption of an O2 molecule followed by a CO molecule on Au LACs, leading to the formation of an intermediate O2CO complex. Upon thermal activation at finite temperatures, the complex is able to proceed to oxidation forming a CO2 molecule and leaving an atomic O impurity in the Au LAC.