Silver Tarnishing Mechanism Revealed by Molecular Dynamics Simulations

Abstract

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 O2, 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.

Conformal Encapsulation of Silver Nanowire Transparent Electrodes by Nanosized Reduced Graphene Oxide Leading to Improved All-Round Stability

“…Although it was observed that R­(nGO) could provide significantly improved thermal and electrothermal (Joule heating) stability, it should also be able to provide protection against chemical and mechanical degradation to enable a broader application that requires long-term reliability. It is well known that for silver, sulfidation rather than oxidation is the dominating mechanism of long-term atmospheric corrosion and is more commonly known as the underlying cause of silver tarnishing . Sulfidation of AgNW has been attributed to trace sulfur compounds in the atmosphere, such as H 2 S and OCS, which react with Ag in the presence of surface-adsorbed water to form Ag 2 S nanoparticle-like features. , The Ag 2 S particles are semiconducting and grow at the expense of Ag, causing the resistivity of AgNW to increase significantly over time.…”

“…It is well known that for silver, sulfidation rather than oxidation is the dominating mechanism of long-term atmospheric corrosion and is more commonly known as the underlying cause of silver tarnishing. 55 Sulfidation of AgNW has been attributed to trace sulfur compounds in the atmosphere, such as H 2 S and OCS, which react with Ag in the presence of surface-adsorbed water to form Ag 2 S nanoparticle-like features. 14,56 The Ag 2 S particles are semiconducting and grow at the expense of Ag, causing the resistivity of AgNW to increase significantly over time.…”

Innovative Codeposition of a Ag–Al2O3 Layer: An Attractive Combination of High Durability and Lack of Cytotoxicity for Public Space Applications

“…These dark spots represent one of the most common defects in samples A and B following the Kesternich test. In fact, silver, in contact with the sulfur dioxide developed in the Kestenich chamber, reacts to form silver sulfide, − resulting in a dark appearance.…”

Failing Forward: Stability of Transparent Electrodes Based on Metal Nanowire Networks

“…[ 81,82 ] Instead, it is agreed among experimental and theoretical studies that the most abundant product of atmospheric corrosion of Ag is Ag 2 S, also known as acanthite, a semiconductor with a monoclinic crystal structure. [ 32,83,84 ] Many studies suggest that sulfidation occurs by reaction of Ag with hydrogen sulfide (H 2 S) in the atmosphere. [ 84 ] Despite the low concentrations of these gases in air, on the order of parts per billion, the presence of water, O 2 and NO 2 can accelerate the reaction process.…”

“…[ 84 ] Despite the low concentrations of these gases in air, on the order of parts per billion, the presence of water, O 2 and NO 2 can accelerate the reaction process. The following reactions have been proposed by multiple studies [ 32,83,84 ] when H 2 S is not abundant, atmospheric carbonyl sulfide (OCS) gas can also become the source of AgNW sulfidation by the following reaction. [ 32,84,85 ] …”