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O: Fachverband Oberflächenphysik
O 16: Nanoscale Heterogeneous Catalysis
O 16.11: Vortrag
Montag, 16. März 2020, 17:45–18:00, TRE Ma
Molecular Dynamics Simulations of Silver Tarnishing — •Gabriele Saleh1,3, Chen Xu2, and Stefano Sanvito3 — 1Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163 Italy — 2Nokia Bell Labs, 600 Mountain Avenue, Murray Hill, NJ, USA — 3a School of Physics, AMBER and CRANN institute, Trinity College Dublin, College Green, Dublin 2, Ireland
Silver is broadly adopted in electronics, although its tendency to degrade by reacting with the environment (Ag tarnishing) represents a severe limitation. Ag is easily tarnished by sulphur compounds, even at ppb concentrations, but hardly reacts with O2, despite thermodynamics predicts both sulphide and oxide to form favorably at ambient conditions[1]. The reactivity disparity is thus to be sought in the reaction dynamics, that is the focus of this contribution. We performed extensive Molecular Dynamics (MD) simulations of Ag/S and Ag/O reactions by employing reactive force fields (ReaxFF [2]). We unearth the different mechanisms of silver oxidation and sulphidation[3], thereby explaining why the latter but not the former takes place. The influence of various defects on Ag reactivity is also considered. Ab initio calculations are performed to confirm and further rationalize the MD findings. Additionally, our results recover (and explain) a number of experimental results from literature. Importantly, for this study we developed new ReaxFF force fields that was extensively tested against ab initio results. [1] P. Patnaik *Handbook of Inorganic Chemicals* [2] A.C.T. van Duin et al., J. Phys. Chem. A 105, 9396 (2001) [3] G. Saleh et al., Angew. Chem. 58, 6017 (2019)