Can graphene surface moisture and adhesion properties be regulated?

Researchers at the University of Illinois at Champaign have successfully regulated the moisture and adhesion characteristics of graphene materials through doping, which has provided possibilities for the development of advanced coating materials and sensors. The research was published in the famous Journal Nano Express.

Graphene has optical transparency and excellent electrical and mechanical properties, which will subvert the surface coating and electrowetting display. The wettability of the material refers to the interaction between the surface of the material and water. It is usually stable without external influence and can be divided into hydrophilic and hydrophobic characteristics. According to different applications of materials, it is necessary to choose between hydrophilic and hydrophobic properties. Taking the electrowetting display as an example, the hydrophilic properties of the display material will be enhanced under the action of an external circuit. Unlike traditional block materials, graphene can be regulated by changing electron density or doping to achieve surface wetting properties.

The researchers found that because graphene was exposed to air and the surface was "polluted" and showed typical hydrophobic characteristics, the study was the first to change the electron density of graphene surface by adding charged polymers and metals(ie doping). In turn, graphene exhibits adjustable wetting properties and realizes hydrophilic and hydrophobic regulatory changes. This discovery revealed for the first time the connection between quantum charge transfer and graphene macroscopic surface wettability. The study opens up a new path to adjust surface coating and electrowetting performance without applying a continuous external current, which will significantly save energy.

In addition, the researchers also studied the surface adhesion of graphene. The electron density of graphene leads to changes in surface adhesion, which determines the interaction of graphene with hydrophilic and hydrophobic water molecules and plays an important role in the construction of graphene-based chemical and biological sensors. Inspired by the results of this study, self-cleaning graphene sensors that can be reused can be developed. The hydrophilic water molecules can be detected first, and then the hydrophilicity of the sensor can be increased by regulating the electron density of graphene, and the hydrophilic water molecules can be separated. The study further broadened the application range of graphene materials.

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