Synthesis of gold nanoparticles with thermal reduction and ultrasonic irradiation

Nanosized particles of noble metals, especially gold nanoparticles, have received great interests due to their attractive electronic, optical and thermal properties as well as catalytic properties and potential applications in the fields on physics, chemistry, biology, medicine and material science and therefore, the synthesis and characterization of AuNPs (gold nanoparticles) have attracted considerable attention from a fundamental and particle point of view [1, 2].To date; a number of procedures including physical and chemical methods for synthesis of AuNPs have been reported. Among the various methods available, thermal decomposition of metal complexes and sonochemical methods are two possible ways of producing metal nanostructures.If the decomposition temperature of metal complex is low and the product is metal, this reaction can be utilized for the synthesis of nanoparticles [3].It has been confirmed that ultrasound can generate acoustic cavitations, which is the formation and violent collapse of the micro bubbles or gas cavities within a liquid.The collapse of the cavities induced the generation of reduction site where the temperature and pressure have been estimated to be over 5000K and 1000atm, respectively. this high temperature and pressure are enough to dissociate water molecules into primary hydrogen radicals and hydroxyl radicals [1, 4].The synthesis of monodisperse nanoparticles, stabilized with polyvinylpyrrolidon (PVP) because of its steric effect covering the surface particles [5, 6].The present work reports the preparation of gold nanoparticles by a simple thermal reduction process and sonochemical method using high molecular weight PVP as both reducing and stabilizing agents. Then these methods have been compared with together.