Solution plasma synthesis of Si nanoparticles

Silicon nanoparticles (Si-NPs) were directly synthesized from a Si bar electrode via a solution plasma. In order to produce smaller Si-NPs, the effects of different electrolytes and applied voltages on the product were investigated in the experiments detailed in this paper. The results demonstrated that the use of an acidic solution of 0.1 M HCl or HNO₃ produced Si-NPs without SiO₂ formation. According to the transmission electron microscopy and electron energy-loss spectroscopy, the obtained Si-NPs contained both amorphous and polycrystalline Si particles, among which the smaller Si-NPs tended to be amorphous. When an alkaline solution of K₂CO₃ was used instead, amorphous SiO₂ particles were synthesized owing to the corrosion of Si in the high-temperature environment. The pH values of KCl and KNO₃ increased during electrolysis, and the products were partially oxidized in the alkaline solutions. The particle size increased with an increasing applied voltage because the excitation temperature of the plasma increased. (paper)