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 Rc∝γ47P-37 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.

Different from the reported results, multiphase (Fe_73.5Si_13.5B₉Nb₃Cu₁)_91.5Ni_8.5 nanocrystalline ribbons (CR-II) show much better degradation capability in Orange II than their metallic glass (MG) counterparts. CR-II ribbons have superior properties, such as high degradation capability, good durability and facile fabrication. In particular, high degradation efficiency could be expected even under an alkaline environment, while most reported zero-valent metals would only be available for acid or neutral environments. Galvanic cells between the α-Fe nanocrystals and intermetallics contribute to the high degradation capability of CR-II by accelerating the α-Fe nanocrystals to lose electrons, leading to the fracture of the azo bond (–NN–). Additionally, 3D nanoporous architectures and 3D flowerlike nanostructure sediments formed during the degradation process are also beneficial to the high degradation capability by promoting mass transport. These findings could provide new clues to design new materials with superior degradation capability and low cost for wastewater treatment.