Graphene prepared by ultrasound
As the special properties of graphite have been known, several preparation methods have been developed. In addition to the chemical production of graphene from GO in a multi-step process, very strong oxidation and reducing agents are required. In addition, graphene prepared under these harsh chemical conditions often contains a large number of defects even after reduction, compared to graphene obtained by other methods. However, ultrasound is a proven alternative method for producing large quantities of high-quality graphene. The method the researchers developed using ultrasound is slightly different, but graphene production is generally a one-step process.

As an example of a specific graphene production process, graphite is added to a mixture of dilute organic acids, alcohols and water, and the mixture is then exposed to ultrasonic radiation. The acid acts as a "molecular wedge" to separate the graphene sheet from the parent graphite. Through this simple process, large quantities of undispersed, high-quality graphene dispersed in water are produced.

Graphene is stripped directly

Graphene can be prepared by ultrasound in organic solvents, surfactants/aqueous solutions or ionic liquids. This means that strong oxidation or reducing agents can be avoided. Stankovich et al. (2007) produced graphene by exfoliation under ultrasound. AFM images showed that flakes of uniform thickness (1nm) were always present after ultrasonic treatment of molten solution of 1mg/ mL graphene oxide. No flakes of greater or less than 1nm thickness were found in these good GO exfoliated samples. It was concluded that under these conditions, A single graphene oxide sheet was obtained by completely peeling off graphene oxide.