Sonochemistry for materials synthesis and catalysis

Abstract

Sonochemistry is linked with the physical and chemical processes resulting due to mechanical energy produced upon ultrasound irradiation in frequencies ranging from 20 kHz to 2 MHz. The key phenomena of sonication are the generation, growth and collapse of the acoustic cavitation which can result in the formation of localized hot spots, with the temperature and pressure reaching up to 5000 °C and 1000 bars, respectively. The enhancement of de-aggregation, better mass transfer, formation of microjets as well as free radicals play essential roles during the synthesis of nanomaterials. The utilization of ultrasound for materials synthesis can help in regulating on-demand specific physicochemical properties of various materials’ classes, such as metals, metal oxides, metal sulfides and metal carbides. Sonochemistry can also potentially give rise to unique properties of materials, often inaccessible with conventional synthesis methods. Moreover, sonolysis, sonocatalysis and the coupling of sonocatalysis with photocatalysis (sonophotocatalysis) as modern catalytic methods have demonstrated promising potential for either selective redox reactions or unselective decomposition of recalcitrant organics.