Synthesis and modification of molecular nanoparticles in electrical discharge plasma in liquids

A review of studies on the synthesis and modification of nanosized particles by electrical discharges in liquid media is presented. The modern understanding of the mechanisms of initiation and features of discharge evolution in liquids are analyzed. By using of the spectroscopic diagnostics, parameters of the discharge plasma in liquids (water, ethanol) are determined. It is shown that the pulsed electrical discharge between electrodes immersed in a nonconducting or weakly conducting liquid, provides a simple and effective method for the synthesis of nanoparticles of different compositions with the average size ranging from 5 to 50 nm. The morphology, phase structure, and composition of the particles formed are defined by the discharge mode and composition of the liquid medium in which the discharge is produced. The conditions for the synthesis of nanosized metal oxides, carbides, and silicides (for example, copper and zinc oxides, titanium and tungsten carbides, gadolinium silicides) were found. Zinc oxide nanoparticles were produced in pulsed electrical discharge plasma in distilled water, and the possibility of their doping with nitrogen atoms during synthesis was demonstrated. Experimental results on the modification of tungsten and copper powders by spark discharge in ethanol are discussed. The possibility to synthesize copper chalcogenides CuInSe2 by electrical discharge treatment of a mixture of copper, indium, and selenium powders was demonstrated.