Chemical method firstly, the oxidation reaction is used to change the graphite oxidation for graphite oxide, by graphite between layer and layer increases with the introduction of oxygen-containing functional groups on the carbon atoms layer spacing, undermine the interactions between the layers.
Methods: Brodie method, Staudenmaier method and Hummers method , the principle of which is to treat graphite with strong acid first,
Then add the strong oxidizer to oxidize.
After the oxidation, the graphite is formed by ultrasonic stripping, and then the reductant is reduced to obtain the graphene.
Commonly used reductants include hydrazine hydrate, NaBH4 and strong alkali ultrasonic reduction. NaBH4 is expensive and easy to retain B elements,
While strong base ultrasonic reduction is simple and environmentally friendly, it is difficult to restore thoroughly. After reduction, there is usually a large amount of residual oxygen-containing functional groups.
Therefore, it is usually used to reduce the graphite oxide by using cheaper hydrazine hydrazine. Hydrazine hydrate reduction ability is to revert to the advantages of strong and hydrazine hydrate is easy to volatilize, no any impurities in the product, in the process of reduction, often to join the right amount of ammonia, on the one hand, increase the ability of hydrazine hydrate reduction,
On the other hand, the surface of graphene can repel each other with negative charge, thus reducing the agglomeration of graphene.
By means of chemical REDOX method, the mass production of graphene can be achieved, and the dispersibility of the intermediate product of graphene oxide in water is better.
It is easy to modify and functionalize graphene, so this method is often used in research of composite materials and energy storage. But because of oxidation,
The lack of some carbon atoms in the ultrasonic process as well as the reduction of oxygen containing functional groups in the process of residue is often made of graphene contains many defects, reduce its electrical conductivity, which limits its on graphene applications in the field of higher requirements for quality.