Photo-induced water-oil separation based on switchable superhydrophobicity- superhydrophilicity and underwater superoleophobicity of the aligned ZnO nanorod array-coated mesh films

Stimulus-responsive surface wettability, especially photoresponsive surface wettability, has been intensively studied. Meanwhile, multifunctional surfaces, especially for the treatment of oil contaminated water, have aroused worldwide attention. Recently, pH-responsive surfaces with controllable oil-water separation have also been reported. However, photoresponsive water-oil separation is still a challenge. Here we report photo-induced water-oil separation based on the switchable superhydrophobicity-superhydrophilicity and underwater superoleophobicity of aligned ZnO nanorod array-coated mesh films, which shows excellent controllability and high separation efficiency of different types of water-oil mixtures in an oil-water-solid three-phase system. The underwater superoleophobicity of the aligned ZnO nanorod array-coated stainless steel mesh film can effectively prevent the mesh film from being polluted by oils. This work is promising in photo-induced water-oil mixture treatments such as water-removal from a micro-reaction system and controllable filtration, and may also provide interesting insight into the design of novel functional devices based on controllable surface wettability.