Morphology-controllable synthesis and application of TiO2 nanotube arrays with "photocatalysis and self-cleaning" synergism

The integration of photocatalytic materials and self-cleaning superhydrophobic materials provides a possibility of combining decontamination and antifouling. Herein, considering the ability of TiO2 in the photocatalytic degradation of pollutants, morphology-controllable TiO2 nanotube arrays (TNAs) were successfully synthesized by adjusting the anodizing and annealing parameters of anodic oxidation. On this basis, superhydrophobic states on 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PTES)-modified TNAs and stearic acid (SA)-modified TNAs were fabricated by means of a facile impregnation method. The TNAs prior to and after modification were characterized by powder X-ray diffraction (XRD) for determining the phase structure, field emission scanning electron microscopy (FESEM) for determining the surface morphology, energy dispersive spectroscopy (EDS) for determining the chemical composition, ultraviolet-visible spectroscopy (UV-Vis) for determining the light absorption performance and a droplet shape analyzer (DSA) for determining surface wettability. The photocatalytic degradation efficiency of methylene blue was investigated, and the synergistic effect of photocatalysis and self-cleaning was well-established from the photocatalytic tests and self-cleaning simulation tests. Compared with untreated TNAs, the modified superhydrophobic TNAs not only maintained better photocatalytic performance, but also possessed the ability to further remove the residual pollutants on the superhydrophobic surfaces by a self-cleaning effect; thus, they have profound impacts on and potential applications in both photocatalysis and self-cleaning.