Oxidation Rate and Crystallinity Dynamics of Silver Nanoparticles at High Temperatures

D Chaparro and E Goudeli, JOURNAL OF PHYSICAL CHEMISTRY C, 127, 13389-13397 (2023).

DOI: 10.1021/acs.jpcc.3c03163

Reactive molecular dynamics (MD)is used to investigate the oxidationkinetics of silver nanoparticles (AgNPs) at temperature ranges of600-900 K by employing a ReaxFF force field. Oxidation of metallicAgNPs leads to a core-shell structure with a silver oxide layerformed at the nanoparticle surface. Higher temperatures and smallerparticle sizes result in faster loss of the fcc crystallinity of theAg core. The (100) facet is more prone to oxidation than the (111)facet, in agreement with previous experiments and computational works.The fraction of the Ag+ ions present in the oxide layerincreases with decreasing particle size, indicating that smaller particleshave the potential to release more Ag+ ions in water, consistentwith ion- selective electrode experiments. A reaction-limited modelis applied to quantify the oxidation rate of nanosilver at varioustemperatures. Higher temperatures lead to faster oxidation. In addition,small particles (d (p) & LE; 6 nm) exhibitlower activation energies, indicating that they are more prone tooxidation than larger ones, consistent with experiments of Al nanoparticles,revealing decreasing activation energy with decreasing particle size.

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