Facile Synthesis of Stable Nanosized Silver Clusters in Plasma Discharge Under Ultrasonic Cavitation

This work is devoted to the study of plasma-chemical processes determined by the combination of the effect of thermally nonequilibrium, low-temperature plasma and intensive ultrasonic vibrations in the regime of intensive cavitation on liquid-phase media. This method for the realization of plasma-chemical transformations has been proven to be of significant interest and to have advantages for the creation of new nano-sized materials with special properties because it allows for varying the electrophysical and acoustic characteristics of the process when carrying out plasma-chemical reactions and fusion reactions. In this work, a novel facile technique for the synthesis of nanosized silver clusters in plasma discharge under ultrasonic cavitation is reported. Such a type of plasma involves the simultaneous effect of high-intensity cavitation and steady electric discharge in a liquid phase between electrodes of desired material. As a result, stable tiny silver nanoclusters with around a 1-nm size and a relatively narrow particle size distribution were obtained using toluene as a liquid medium. The nanoclusters were characterized with dynamic light scattering, transmission electron microscopy, electron diffraction, and optical methods. The results confirmed the formation of nanoclusters with an absorbance peak around 300 nm and the absence of 400-nm peaks typical for silver nanoparticles. Fluorescence tests allowed for establishing the amorphous structure of the synthesized nanoclusters occupying the intermediate position between few-atom nanoclusters and nanoparticles. The nanoclusters obtained were proven to be stable for more than 3 months. The experiments also revealed the possibility of performing high-temperature plasma-chemical reactions that can be applied in fusion technology.