Ultrasonic method for graphene dispersion

The chemical method first uses oxidation reaction to oxidize graphite to graphite oxide, and increases the interlayer spacing by introducing oxygen-containing functional groups on the carbon atoms between the graphite layers, thereby weakening the interaction between the layers.

Common oxidation methods include Brodie method, Staudenmaier method and Hummers method. The principle is to first treat graphite with strong acid and then add strong oxidant for oxidation. The oxidized graphite is exfoliated by ultrasonic to form graphene oxide, and then a reducing agent is added for reduction, thereby obtaining graphene.

Commonly used reducing agents are hydrazine hydrate, NaBH4 and strong alkali ultrasonic reduction. Because NaBH4 is expensive and easy to retain B element, although the operation of strong alkali ultrasonic reduction is simple and environmentally friendly, it is difficult to reduce completely, and there is usually a large amount of oxygen-containing functional groups left after reduction. Therefore, relatively cheap hydrazine hydrate is usually used to reduce graphite oxide. . The advantages of hydrazine hydrate reduction are that the reduction ability is strong and hydrazine hydrate is easy to volatilize, and no impurities remain in the product. In the reduction process, an appropriate amount of ammonia water is usually added to improve the reducing ability of hydrazine hydrate on the one hand, and graphite on the other hand. The surfaces of the graphene repel each other due to the negative charge, which in turn reduces the agglomeration of the graphene.

Graphene can be prepared in large quantities by chemical redox method, and the intermediate product graphene oxide has good dispersibility in water and is easy to dry to achieve modification and functionalization of graphene. Therefore, this method is often used for dry composite materials. Energy storage and other research. However, due to the lack of some carbon atoms in the process of oxidative ultrasonication and the residue of collar-containing functional groups in the reduction process, the prepared stonene often contains more bell traps, which reduces its conductivity, which limits its impact on the quality of graphene. Applications in demanding fields