In order to effectively utilize graphene for various applications, researchers are trying to develop 3D graphene structures from 2D graphene layers. Such kind of graphene structures are known as 3D graphene materials. There are different types of 3D graphene materials which are classified as macroscopic and microscopic. Graphene foams, sponges, porous graphene films, aerogels etc. fall under the category of macroscopic 3D graphene materials. These materials will be generally greater than 100 μm in either one or more dimensions. They generally possess porous architecture with high surface area and low density. Whereas, those 3D graphene materials which are less than 100 μm in all dimensions fall under microscopic category. They are generally powders macroscopically but, will be of micrometer or nanometre scale 3D structures.
Developing 3D graphene materials
The 3D graphene materials can be in the form of millispheres, fibers, films, hydrogels, sponges, honey comb like structures, coral like structures, flower like structures, printed architectures etc. Such 3D graphene structures can be prepared by different methods such as impregnation pyrolysis, template synthesis, freeze drying, electrospinning, 3D printing etc.
Applications
Due to superior properties, 3D graphene materials possess varying electronic applications including energy storage, energy conversions, flexible electronic displays, solar cells etc. Additionally, they can be used as catalyst support and as adsorbent for filtration applications.
3D graphene as electrode material
In recent years, the application of 3D graphene material as electrodes in supercapacitive devices, anodes in metal-ion batteries, cathodes in Li-S batteries, cathodes in metal-air batteries, electrodes for hydrogen evolution reactions, fuel cells, flexible electronics, counter electrodes in dye sensitized solar cells etc. have been explored.
3D graphene as active sensing material
Sensors are those devices which gives response to chemicals, pressure, temperature, humidity etc. 3D graphene structures are widely studied for developing strain sensors, gas sensors, electrochemical sensors etc.
3D graphene materials as conductive supports
Owing to the large surface area, high electrical conductivity and porosity, 3D graphene materials are widely studied for developing conducting support for polymers, metal nanoparticles, metal oxide nanoparticles, enzymes etc. As conductive support, 3D graphene material will help to ensure high dispersion of the deposited materials. This will help for proper charge movement and efficient mass transfer.
3D graphene materials as adsorbents
Since graphene possess large surface area, the 3D graphene material can be used as adsorbent in air and water filtration applications. The porous nature of 3D graphene materials help to effective adsorb large molecules like oils, gases, antibiotics, dyes, heavy metal ions etc.
3D graphene materials as thermal mediators
3D graphene materials are known to possess tunable thermal conductivity and broad light absorption range. Because of these reasons, 3D graphene materials are gaining attention in thermal management and solar thermal energy conversions
Reference : https://dx.doi.org/10.1021/acs.chemrev.0c00083