Self-assembly of graphene oxide aerogels by layered double hydroxides cross-linking and their application in water purification

Abstract

Self-assembly based on graphene building blocks are an important strategy for three-dimensional (3D) architectures, but their fabrication and application in water purification remain challenging. Here, we report a facile one-step approach to prepare 3D graphene oxide (GO) hydrogels and aerogels containing nanoscaled layered double hydroxides (LDHs). The LDHs acted as cross-linking agent molecules (“buttons”) to join GO nanosheets into a 3D network via charge-assisted hydrogen bonds and lattice–lattice cation–π interactions. The resultant aerogels exhibited high hydrophilicity and excellent structural stability/plasticity in water environments, which guarantee the availability of their effective active sites in aqueous solution and overcome the utilization restrictions of neat GO aerogels due to their fragile morphology. The obtained LDH + GO aerogels showed a high capability for removal of dye (methylene blue) and heavy metal (Cd²⁺) pollutants from water. The addition of LDH nanoparticles assisted the aerogels in maintaining their 3D monoliths and made it easy for separation and collection after use, and improved the adsorption capacities for environmental pollutants via reducing the stacking of GO sheets and exposing more active adsorption sites. Thus the obtained LDH + GO aerogels have a great potential for water purification as highly efficient and stable adsorbents.