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.