Silver Tarnishing Mechanism Revealed by Molecular Dynamics Simulations

Abstract

The mechanism of silver-oxygen and silver-sulphur reactions is revealed by means of molecular dynamics simulations, performed with reactive force fields purposely built and extensively tested against quantum chemical results. Different reaction mechanisms and rates for Ag-O and Ag-S emerge. This study solves the long-lasting question as to why silver exposed to the environment is strongly vulnerable to sulphur corrosion (tarnishing) but hardly reacts with O2, despite thermodynamics predicts both oxide and sulphide to form. The reliability of the simulations results is confirmed by the agreement with a multitude of experimental results from literature.