MOFs-induced high-amphiphilicity in hierarchical 3D reduced graphene oxide-based hydrogel

Abstract

Micro-nano surface with high-amphiphilic structures possesses fascinating physical properties and promising applications in many areas. Herein, we reported a three dimensional (3D) porous hierarchical architecture with internal crosslinked network structures constructed from metal-organic frameworks (MOFs) and graphene oxide (GO) through a facile self-assembly hydrothermal method. In contrast to conventional 3D graphene hydrogel with strongly hydrophobic structures, the resulting composite exhibited high-amphiphilic features with both highly hydrophilic and oleophilic ability, which could absorb water and oils simultaneously, owing to the synergistic effect between MOFs and reduced graphene oxide. MOFs acted as a dopant and intercalated between reduced graphene oxide layers, which could largely increase the specific surface areas of graphene hydrogels (GH) and artistically adjust the surface structures of pristine GH as well. Accordingly, the 3D porous hierarchical MIL-101-GH materials showed great absorption capacity for oil and water. The advantages of this high amphiphilic properties were proved by constructing a biphasic catalytic system with the introduction of molecular sieve into the 3D MIL-101-GH hybrid. As a result, the designing functionalized foam exhibited good catalytic performance in heterogeneous catalysis for epoxidation of olefins without addition of co-solvents.