Oxidative Dissolution of Silver Nanoparticles by Dioxygen: A Kinetic and Mechanistic Study

We have recently reported a kinetic and mechanistic study on oxidative dissolution of silver nanoparticles (AgNPs) by H2O2. In the present study, the parameters that govern the dissolution of AgNPs by O2 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 (kapp) of AgNPs (10±2.8 nm) by O2 is about 100‐fold slower than that of H2O2. The reaction rate is first‐order with respect to [Ag0], [O2], and [Tris]T, and inverse first‐order with respect to [Ag+] (where [Ag0]=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 (O2−) 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 O2 is proposed. Dissolution is the solution! Parameters that govern the dissolution of AgNPs by O2 were investigated. The reaction rate is first‐order with respect to [Ag0], [O2], and [Tris]T, and inverse first‐order with respect to [Ag+]. On the basis of kinetic and trapping experiments, an amine‐activated pathway for the oxidation of AgNPs by O2 is proposed.