Paper PS-ThP23
Exotic Shapes of Gold Nanoparticles Synthesized with Plasma in an Aqueous Solution

Thursday, October 18, 2007, 5:30 pm, Room 4C

Plasma materials processing in liquid phase has a potential of an industrial process for metal nanoparticles since this process would realize extremely rapid reaction under a high pressure. Moreover, this method does not require a reducing agent to fabricate metal nanoparticles from the solution containing metal ion and extraction process of residues. In our previous study, gold nanoparticles were successfully synthesized with discharge in an aqueous solution. In this study, we reported the shape change of the nanoparticles fabricated with discharge in the aqueous solution. In order to obtain various shapes of nanoparti1cles, the amount of additives in the solution was changed. Gold nanoparticles were synthesized through reduction with a discharge in the aqueous solution containing chlorauric acid as metal source. Gelatin was added to the aqueous solution as a stabilizer. Electric conductivity of the solution was varied from 500 to 2500 μS/cm in order to obtain suitable condition for generation of discharge by the addition of KCl. The discharge was generated by a pulsed power supply. The applied voltage and the pulse width were ca. 1600 V and 2 μs, respectively. The gold nanoparticles were observed by transmission electron microscopy (TEM) and analyzed by energy dispersive X-ray spectroscopy (EDS). Plasmon band of the gold nanoparticles were measured by ultraviolet-visible spectroscopy (UV-Vis). TEM images show the presence of exotic shapes of gold nanoparticles, that is, triangle sheet, pentagon, hexagon and so on. The exotic shapes were generated when the concentration of KCl became higher. The synthesis of nanoparticles using other surfactants (e.g. CTAB) with discharge was also demonstrated. These results suggested that the shapes of the nanoparticles strongly depend on KCl or surfactant concentrations in the solution.