Facile one-pot synthesis of superhydrophobic reduced graphene oxidecoated polyurethane sponge at the presence of ethanol for oil-water separation

Polyurethane (PU) sponge has attracted significant interest in oil-water separation for its unique three-dimensional porous structure. However, its oil-absorption efficacy is dramatically limited by its poor hydrophobicity. Herein, superhydrophobic reduced graphene oxide-coated polyurethane (RGO@PU) sponge has been facilely fabricated using a one-pot solvothermal method at the presence of ethanol. The formation of RGO-coating layer on the surface of PU sponge is promoted with the assistance of ethanol, because the addition of ethanol decreases the surface tension of aqueous GO solution and improves the wettability of PU sponges. The as-prepared RGO@PU sponge with a superhydrophobic surface (water contact angle of 153 degrees) exhibits a high oil-absorption capacity of more than 37 times of its original mass. A strong recycling absorption capacity (34 g/g) can be observed even after the RGO@PU sponge has experienced 50 oil absorption-desorption cycles. Moreover, our RGO@PU sponges have potential application as a promising absorbent for oil-water separation due to their fast oil-absorption rate (the oil can be removed in 5 s) and high oil-water separation efficiency (similar to 99%).