Three-dimensional biomimetic superhydrophobic nickel sponge without chemical modifications for efficient oil/water separation

The frequent oil spill accidents and a large amount of industrial oil wastewater discharges had caused serious economic losses and damage to the marine ecological environment. Hence, oil–water separation technology had received increasing attention from researchers. Herein, three-dimensional (3D) nickel sponge was prepared via a facile hydrothermal reduction route. The nano-spines structure of nickel sponge could exhibit superhydrophobic/superlipophilic properties without further hydrophobic modification by low-surface-energy chemicals. Due to the opened hierarchical porous structures and higher porosity, nickel sponges have excellent adsorption capacity for various oils and organic solvents. Nickel sponge has good resistance to ultraviolet radiation, corrosive aqueous solution ability, can be used for long-term outdoor applications. Moreover, the nickel sponge can also selectively absorb oil from oil/water mixtures under turbulent flow conditions. In addition, nickel sponges can continuously and rapidly collect oil from immiscible oil/water mixtures with the aid of a vacuum. Nickel sponge can also efficient selective filter oil/water mixture with a high separation efficiency over 97%. Due to the combination of metallic properties and the low density, nickel sponges are expected to have potential applications in oil absorption, flexible electrodes and industrial catalysis.