Oxidative dissolution of silver nanoparticles by dioxygen: A kinetic and mechanistic study

Abstract

We have recently reported a kinetic and mechanistic study on oxidative dissolution of silver nanoparticles (AgNPs) by H 2O 2. In the present study, the parameters that govern the dissolution of AgNPs by O 2 were revealed by using UV/Vis spectrophotometry. Under the same reaction conditions (Tris-HOAc, pH 8.5, I=0.1 M at 25 °C) the apparent dissolution rate (k app) of AgNPs (10±2.8 nm) by O 2 is about 100-fold slower than that of H 2O 2. The reaction rate is first-order with respect to [Ag 0], [O 2], and [Tris] T, and inverse first-order with respect to [Ag +] (where [Ag 0]=total concentration of Ag metal and [Tris] T=total concentration of Tris). The rate constant is dependent on the size of AgNPs. No free superoxide (O 2 -) and hydroxyl radical (·OH) were detected by trapping experiments. On the basis of kinetic and trapping experiments, an amine-activated pathway for the oxidation of AgNPs by O 2 is proposed. Copyright © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.