Nanostructured TiO2/CuO dual-coated copper meshes with superhydrophilic, underwater superoleophobic and self-cleaning properties for highly efficient oil/water separation

Abstract Oil-contaminated water caused by either oil spill disasters or industrial disposal has posed a global risk to environmental sustainability and human health. To address the ever-growing need for highly efficient separation of oil/water mixtures, nanostructured TiO2/CuO dual coatings were fabricated on the copper mesh by a combination of electrochemical anodization and layer-by-layer self-assembly deposition to render its surface with superhydrophilic, underwater superoleophobic and self-cleaning functionality. Cu(OH)2 nanoneedle arrays (NNA) were vertically grown from the copper mesh surfaces by electrochemical anodization processes, followed by the deposition of TiO2 multilayer on the Cu(OH)2 NNA via layer-by-layer assembly prior to being calcinated to form TiO2/CuO dual coatings. The nanostructured TiO2/CuO NNA dual-coated copper meshes were demonstrated to exhibit a high separation efficiency (oil residue content less than 20 ppm), excellent water flux (more than 80 kL·h−1·m−2), and desirable self-cleaning ability under ultraviolet (UV) illumination. The photo-catalytic ability of the deposited TiO2 layers enabled the facile and rapid removal of the oil contaminants on the mesh surface under UV illumination to recover oil/water separation ability of the as-fabricated mesh for recycle use. With the adherent features of superhydrophilicity, underwater superoleophobicity and self-cleaning ability, the proposed TiO2/CuO NNA dual-coated meshes are potentially useful in practical oil/water separation applications.