Do you know the principle and process of preparing graphene by ultrasonic equipment?

"2019 Travel of Dispersed Grinding Equipment Enterprises in the Pearl River Delta Region" was developing and using ultrasonic equipment to prepare graphene. It is understood that the ultrasonic method for peeling off graphene is mainly due to the cavitation effect of ultrasound. When the liquid is under the action of high-energy ultrasound, the tiny bubbles in the liquid will periodically undergo the process of growth, contraction and rupture. The shock wave generated by the rupture will immediately act on the surface of the graphite, and the corresponding graphite will generate compressive stress wave. According to the principle of compressive stress wave, when the compressive stress wave propagates to the surface of the graphite, The graphite body will reflect and produce tensile stress. Therefore, when countless tiny bubbles break, the tensile stress between the graphite sheets will increase continuously until the graphene sheets are stripped.

The process of ultrasonic preparation of graphene is to assemble the ultrasonic drive power supply, reactor body, ultrasonic vibrator, material inlet and material pump according to Figure 1. The cooling circulating water inlet is connected with the external water source, the cooling circulating water outlet is connected with the external water outlet pipe, and the material flow regulating valve, feed control valve, discharge control valve and sampling port control valve are closed. Using graphite (as shown in Figure 2: a) as raw material, the expanded graphite with low oxidation degree (as shown in Figure b) is obtained after pre-intercalation, and added to some organic solvent or water to form graphene pretreatment solution (as shown in Figure c); With the help of ultrasound, heating or air flow, graphene dispersion with good dispersion is obtained (as shown in Fig. d); Then, the dispersion is separated by centrifuge or filtered by filter press to obtain graphene chips.


When graphene is matched with the surface of organic solvent, their interaction can balance the energy needed to peel off graphene sheets, and then through ultrasonic treatment, ultrasound provides the peeling force to play a stripping effect. Increasing the ultrasonic time can improve the yield of graphene very well. Adjusting the ultrasonic power of the ultrasonic power supply also has a significant impact on the peeling effect of graphene. The peeling effect of graphene depends on the matching degree of the ultrasonic power and the van der Waals force between graphene layers. When the ultrasonic power is properly increased, the tensile stress generated on the surface of graphene is greater than the van der Waals force between graphene layers, and the peeling effect will also increase significantly.


The experimental study found that the graphene pretreatment solution formed by the hot intercalation of graphite can easily peel off graphene under the action of ultrasonic equipment, and the graphene lamella is basically below 10 layers. As the ultrasonic preparation principle of graphene is based on "ultrasonic cavitation", it will not cause structural defects of graphene, and ensure its integrity of morphology and performance, which is of great significance for large-scale production of graphene.