Controlling the shell formation in hydrothermally reduced graphene hydrogel

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Graphene hydrogels/aerogels are 3D graphene materials with applications in energy storage, pollutant adsorption, and gas sensing.
• The exterior shell structure of hydrogels influences their properties and performance.
• Controlling shell formation is key to optimizing graphene hydrogel functionality.

Purpose of the Study:

• To identify, characterize, and control the formation of the exterior shell structure in graphene hydrogels.
• To investigate the role of surface anchoring of graphene oxide in shell formation.
• To develop a method for suppressing shell formation and creating hydrogels with accessible porous structures.

Main Methods:

• Hydrothermal reduction of graphene oxide to form graphene hydrogels.
• Analysis of shell structure formation and properties.
• Controlled weakening of graphene oxide surface anchoring via mild thermal or chemical pre-reduction.
• Characterization of resulting graphene hydrogels for structural and electrical properties.

Main Results:

• Graphene hydrogels conventionally form a compact, highly ordered exterior shell with higher electrical conductivity compared to the porous bulk.
• Shell formation is dependent on graphene oxide anchoring at liquid-air and liquid-container interfaces.
• Weakening surface anchoring successfully suppressed shell formation, resulting in hydrogels with lower volume reduction and accessible porous structures.

Conclusions:

• Shell formation in graphene hydrogels can be effectively controlled by manipulating graphene oxide surface anchoring.
• Suppressing shell formation leads to improved accessibility of the porous bulk structure and reduced volume shrinkage.
• This controlled fabrication method offers a pathway to tailor graphene hydrogel properties for specific applications.