Understanding the relationship between particle size and ultrasonic treatment during the synthesis of metal nanoparticles.

[Display omitted] • The influencing mechanism of ultrasound on the size of Cu nanoparticles is studied. • The mean size and size dispersion are significantly reduced ultrasound treatment. • A competition model between surface energy and ultrasonic force is proposed. • An exponential relation of between particle size and ultrasonic power is revealed. • Ultrasonic power and surface energy are keys to control the final particle size. Ultrasonic treatment is an effective method for size refinement and dispersion of nanomaterials during their synthesis process. However, the quantitative relationship between ultrasonic conditions and particle size in the synthesis of metal nanoparticles has not been fully revealed. In this study, Cu nanoparticles were synthesized via the wet-chemical redox method under ultrasonic treatment, and statistical analysis on the evolution of particle size distribution was carried out. It was found that the particle size decreased exponentially with increasing ultrasonic power. A quantitative model was then proposed to describe the influence of ultrasonic power on the size distribution of metal nanoparticles from the perspective of the competition between the surface energy and the ultrasonic force. A relational expression of R c ∝ γ 4 7 P - 3 7 was revealed, and it was proved to fit well with the experimental results. Our study provides new experimental basis and theoretical method for understanding the mechanism of ultrasonic-induced size refinement of metal nanoparticles. [ABSTRACT FROM AUTHOR]