Characteristics of nano-metal colloid prepared by electrical spark discharge method

Background: This study used Electrical Spark Discharge Method (ESDM) to fabricate the nano-Au, nano-Ag and nano-Cu colloid. The spark wears down the surface of the electrodes and gets nano-metal particles at standard temperature and pressure and without adding any other chemical materials in the deionized water. Methods: The nano-metal particles are examined by UV-Visible Spectroscopy, Zetasizer, Transmission Electron Microscope, and Energy Dispersive X-ray Analysis and are proven to be nano-metal colloid. Under the comparison of different parameters (discharge pulse width, HV, Ip), the size of nano-metal particles increases with the level of Ip. Results: Under the experiment of light or dark, most of the Absorbance of the nano-Au and nano-Ag colloid is higher than that of the environment under strong light irradiation as long as it is prepared in a pure black environment. The nano-Au and nano-Ag colloid prepared by ESDM have a zeta potential exceeding the absolute value of 30 mV, no matter which parameter is applied or whether there is illumination or not. Conclusion: It represents a good suspension stability of the nano-Au and nano-Ag colloid, but the nano-Cu colloid does not have this feature. The suspension stability is not good.