Prospective routes for the synthesis of graphene-based hydrogels

Graphene-based hydrogels (GBHs) are getting a lot of attention because they have special features like strong electrical conductivity, high strength, and great heat resistance. Their properties make them excellent for biomedical, environmental, and energy storage applications. This chapter describes GBHs synthesis techniques that affect material structure and characteristics. Common methods include hydrothermal, chemical reduction, crosslinking agents to help self-assemble, in situ polymerization, and freeze-drying. In hydrothermal synthesis, a solution of GO is heated to high temperatures and pressures in order to encourage gelation by stacking interactions between π-π bonds. Chemical reduction involves reducing graphene oxide (GO) in aqueous solutions using agents such as hydrazine or ascorbic acid. This process causes graphene oxide to self-assemble into a hydrogel network. Self-assembly of GBHs using crosslinking agents means using chemicals to connect graphene sheets, creating a solid three-dimensional structure. The process of in situ polymerization results in the formation of hydrogels from monomers. The freeze-drying method for making GBHs requires freezing a graphene mixture followed by vaporization of the liquid under pressure, forming a highly permeable, lightweight, and physically stable hydrogel. Given the significance of synthesis, this chapter critically reviews basic GBHs preparation research, using contemporary relevant literature to explain their benefits and challenges.