All-Carbon Hybrid Aerogels: Synthesis, Properties, and Applications

Carbon hybrid aerogels (CAs), formed by different carbon allotropes and/or nanostructures, are reviewed. Hybrid aerogels are composed by CNT-graphene (graphene oxide and reduced graphene oxide), CNT-carbon foam, graphene- hollow carbon semispheres, spheres, capsules, and foam. Both MWCNTs and SWCNTs are known to form hybrid aerogels. The addition of carbon or graphene quantum dots or lanthanide oxides provides luminescent properties of the formed composites. Third counterparts can be metals, their oxides, hydroxides, and sulfides, as well as some polymers. Hybrid aerogels are generally synthesized through freeze-drying and pyrolysis as the last reaction steps and possess high specific surface area and certain electric conductivity. Main applications of carbon hybrid aerogels are in the areas of super-capacitors, sensors, fuel cells, adsorption of organic pollutants and heavy-metal ions, and microwave absorbers, among others.