Photocatalytically Active Superhydrophilic/Superoleophobic Coating

Hydrophilic materials are easily fouled by organic contaminants owing to their high surface energy, and this oil-fouling problem severely hinders their use in practical applications. To address this challenge, herein, a hydrophilic coating with oil repellency and photocatalytic activity is developed by a spray-casting process. In the air surrounding, a water droplet spreads over the coating surface completely, while oil droplets exhibit contact angles more than 150 degrees and moving on the coating freely. The water-wetted coating still had oil repellency, as the water layer on the coating surface can act as a lubricant to repel oil. Although methylene blue aqueous solution contaminates the coating by wetting it completely, these water-soluble organic molecules can be removed by UV illumination, due to the photocatalytic activity of the coating. Exploiting its water-attracting and oil-repelling properties, the coating deposited on a copper mesh is applied as a multiplatform for oil-water separation with high separation efficiency. This study provides a novel and efficient way to solve the oil-fouling problem of hydrophilic materials.