Silver Tarnishing Mechanism Revealed by Molecular Dynamics Simulations

KGaA, Weinheim The mechanism of silver?oxygen and silver?sulfur 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 why silver exposed to the environment is strongly vulnerable to sulfur corrosion (tarnishing) but hardly reacts with O 2 , despite the thermodynamic prediction that both oxide and sulfide should form. The reliability of the simulation results is confirmed by the agreement with a multitude of experimental results from the literature.