Thermal Decomposition of Silver Acetate: Physico-Geometrical Kinetic Features and Formation of Silver Nanoparticles

The thermal decomposition of silver acetate (CH3COOAg) was investigated to reveal the factors controlling the formation of Ag nanoparticles (NPs). The overall kinetic behavior was interpreted as partially overlapping two reaction steps using systematic kinetic and morphological analyses. Although the apparent activation energies were comparable (approximately 75 kJ mol(-1)), the initial reaction step was regulated by the first order law because of the consumption of reactive sites on the end surfaces of columnar crystals, whereas the subsequent reaction step advanced by shrinkage of the side surfaces of the crystals with an accelerating linear shrinkage rate, resulting in slimming of the crystals. A large surface area of the reactant crystals was exposed to the reaction atmosphere during the course of the reaction by the self-induced migration of the Ag product to the surfaces of the Ag-NP aggregates formed at certain parts of the reactant surfaces. As a result, the atmospheric water vapor affected the kinetic behavior by significantly lowering the reaction temperature. As a possible explanation for these phenomena, a physical mechanism involving evaporation of the reactant and simultaneous condensation of the product is proposed herein.