Due to the increase in oil spill accidents and discharge of oily wastewater, it is urgent to develop functional materials to separate oil from oil/water mixtures. In this work, the kaolin-coated meshes were fabricated by a facile coating method to construct a micro-hierarchical surface and controllable pore size for the separation of various oil/water mixtures. The obtained meshes exhibits super-hydrophilicity, underwater super-oleophobicity with underwater oil contact angle >150° and outstanding oil/water separation efficiency above 99% and f...