Continuous ZIF-8/reduced graphene oxide nanocoating for ultrafast oil/water separation

Continuous ZIF-8/reduced graphene oxide (RGO) nanocoating is fabricated by growing ZIF-8 on RGO-coated polyurethane (PU) foam. Surface modification of PU foam can be easily achieved by immersing the PU foam in GO solution, followed by mild thermal treatment to turn the GO layer into RGO layer. Adhesion between polymer foam and ZIF-8 layer was enhanced by the inserted RGO layer because oxygen-containing groups of RGO could interact with Zn2+ precursor of ZIF-8 localizing the layer growth preferentially on the surface of RGO. The synergetic hydrophobic/oleophilic properties of RGO and ZIF-8 enable selective oil absorption of PU foam with an absorption capacity of 15–35 g/g depending on the viscosity of organic solvents. Most of all, the ZIF-8/RGO coated PU foam can filter organic solvent selectively via vacuum filtration, showing ultrafast hexane flux up to 800,000 Lm−2 h−1 and no water flux.