Determining the reaction kinetics of halide salts with silver nanoparticles is important for understanding the fate of the nanoparticles in various environments.  We have found that addition of chloride ion in the form of NaCl causes a layer to form which inhibits further reaction on the nanoparticle surface.  Neither bromide nor iodide ions form such a passivating layer and, in fact, both strongly enhance the oxidation of the surface.  Studies involving halide-induced aggregation of the nanoparticles show that the surface charge is significantly reduced when chloride ion is added. We propose that the charge reduction is due to replacement of adsorbed citrate (used as a capping agent in the silver nanoparticle synthesis) by adsorbed AgCl2-, but an alternate explanation is partial desorption of the citrate ions when a layer of AgCl is formed.  We are investigating these possibilities through mixed-halide and variable-temperature studies.

Surface affects of halides on silver nanoparticles

243rd National Meeting (2012)

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