Mechanically Robust Fish-Scale Microstructured TiO₂-Coated Stainless Steel Mesh by Atomic Layer Deposition for Oil-Water Separation

Recently, inorganic-material-coated separation membranes have been widely applied in the field of oil/water separation due to their advantages of high efficiency and low energy consumption. However, usual preparation methods including electrodeposition, hydrothermal method, sol-gel method, and liquid phase immersion method have complex preparation processes or poor adhesion between coatings and substrates, leading to their poor mechanical stability and limiting their practical application. Herein, a mechanically robust TiO2 coating with a unique fish-scale structure on a stainless steel mesh was prepared by the atomic layer deposition (ALD) technique, which can efficiently separate oil/water mixtures with a high flux of 1.43 × 105 L·m-2·h-1. The separation efficiency can reach more than 99.0% for various oil-water mixtures, and the intrusion pressure for various oils is higher than 1.64 kPa. More importantly, a series of mechanical stability tests, such as friction test, impact test, adhesion test, and kneading test, show that the obtained TiO2-coated stainless steel mesh has excellent mechanical stability. The soaking experiment in 1 M HCl, NaOH, and NaCl corrosion solutions shows that the mesh membrane has good chemical stability. Meanwhile, based on the excellent photocatalytic capacity of the TiO2 coating, the obtained TiO2-coated stainless steel mesh has special self-cleaning and antifouling ability. This work provides an efficient strategy using ALD technology for producing a mechanically robust functional coating separation membrane, which has great practical application value in the field of oil-water separation.