Preparation of Graphene Colloids in Different Dispersing Devices by Electric Spark Discharge Method and Analysis of Their Suspension Stability

Abstract

In this study, electrical discharge machine (EDM) was used to prepare graphene colloids by the electric spark discharge method (ESDM). Machine-lathed 99% pure graphite rods were used as the electrodes, deionized water (DI water) was used as the dielectric liquor, and a magnetic stirrer and ultrasonic cleaner were used as the dispersing devices. According to the analysis results from ultraviolet-visible spectroscopy (UV-Vis), Zetasizer, and transmission electron microscope (TEM), the characteristic wavelength of graphene was 260 nm with an absorbance of 0.219 and a zeta potential of -36.6 mV, and many graphene laminates could be seen based on the microscale. This study discussed the two different dispersing devices used to make graphene colloids and analyzed their impact on suspension stability. The results showed that a magnetic stirrer was suitable for making graphene colloids with high suspension stability and low concentration, while an ultrasonic cleaner was suitable for making graphene colloids with low suspension stability and high concentration. The graphemes made by the chemical method are difficult to suspend in water and chemical or dispersant additives are required to maintain their properties; furthermore, which increases the production time. However, with no need for chemical additions and a short preparation time, ESDM is a safe, environmentally-friendly, and fast green manufacturing method.