Covalently cross-linked graphene oxide aerogel with stable structure for high-efficiency water purification

Porous graphene-based aerogels (GAs) hold great promise for water purification due to their fascinating properties. However, weak connections between the graphene oxide nanosheets cause instability and incompressibility in GAs during practical applications. Herein, the small organic molecule of cysteamine was selected as a covalent cross-linker to fabricate GAs through a facile one-step synthesis method. The porosity and mechanical stability of GAs were simultaneously improved due to strong covalent cross-linking between the graphene oxide nanosheets via cysteamine as the linkage. The resultant graphene/cysteamine aerogels (GCAs) were compressible with excellent structural stability under different acid, base, and organic solution conditions. The maximum oil absorption capacity of the GCAs reached as high as 251 g/g and did not obviously decrease even after regeneration by squeezing. In addition, the GCAs exhibited a high adsorption capacity for common dyes, such as methylene blue (207.8 mg/g) and methyl orange (70.2 mg/g). As expected, the as-prepared aerogels with high adsorption capacities, structural stability and excellent compressibility, have great potential as recyclable and durable materials for water purification.