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 H 2 O 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 2 O 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.