Stearic acid modified Co2+-doped ZnO: The construction of micro-nano structure for its superhydrophobic performance and visible-light photocatalytic degradation of methylene blue

Herein, the Co2+-doped ZnO nanoarrays with high photocatalytic activity were grown on the stainless steel wire mesh (Co2+-ZnO@SSM) by the hydrothermal method, and the special micro-nano structure with high surface roughness was obtained through stearic acid (STA) surface modification for the superhydrophobicity. By changing the concentrations of STA, the hydrophilic and hydrophobic structure of Co2+-ZnO/STA@SSM could be controlled, and the water contact angle in air reached 154.9° when the STA concentration was 0.04 mol/L. In different oil/water mixtures, the Co2+-ZnO/STA@SSM showed excellent oil/water separation efficiency and separation flux, and after 16 separation cycles and bending tests, the separation efficiency remained above 89%. In addition, the Co2+-ZnO/STA@SSM still maintained excellent visible photocatalytic activity, and the photocatalytic efficiency for methylene blue degradation could reach 93% in water. This dual-functional Co2+-ZnO/STA@SSM membrane with visible-light photocatalysis and oil/water separation provides a potential purification strategy for the complex industrial wastewater.