抄録
Sonochemical synthesis of various types of nanoparticles and nanostructured materials has received much attention in recent years. This is due to the unique reaction routes induced by acoustic cavitation in solution: the acoustic cavitation provides extreme conditions of transient high temperature and high pressure within the collapsing bubbles, shock wave generation and radical formation. The sonochemical reduction of Au(III) to produce Au nanoparticles was performed in the presence of a small amount of 1-propanol at different frequencies. Ultrasonic irradiation was carried out with two types of ultrasound irradiation systems: a horn type sonicator (20kHz) and a standing wave sonication system with a series of transducers operating at different ultrasound frequencies (213kHz, 358kHz, 647kHz, 1062kHz). An aqueous solution of HAuCl_4 (0.2mM, 70mL for 20kHz, 200mL for the others frequencies) was added to the reaction vessel and then purged with argon. As an accelerator for the reduction of Au(III) ions, 1-propanol was injected into the solution. The synthesized Au nanoparticles were analyzed by TEM. The rate of sonochemical reduction of Au(III) to produce Au nanoparticles in aqueous solutions containing 1-propanol has been found to be strongly dependent upon the ultrasound frequency. The size and distribution of the Au nanoparticles produced can also be correlated with the rate of Au(III) reduction, which in turn is influenced by the applied frequency. Our results suggest that the rate of Au(III) reduction as well as the size distribution of Au particles are governed by the chemical effects of cavitation and are not significantly affected by the physical effects accompanying ultrasound induced cavitation.
