Practical significance in terms of the long-term effective application of photocatalytic coatings is greatly challenged by its easy pollution and poor self-cleaning performance. In this paper, a self-cleaning photocatalytic WO 3 -TiO 2 nanorod (MWT) /PDMS building coating (MWT coating) was prepared by spraying methods. The surface hierarchical structure fabricated by MWT and PDMS was a crux to construct a superhydrophobic surface, which endowed MWT coating with self-cleaning performance. Besides, the MWT coating exhibited prominent durability and antifouling property after 450 d practical application of the external wall. The excellent self-cleaning property of the coating was confirmed by the removal and resistance to the adhesion of powder particles. Meanwhile, the photocatalytic properties of MWT endowed MWT coating with the ability to degrade organic pollutants on the surface. The color difference of the coating polluted by methyl red was only 1.18 and 4.77 after 24 h UV and visible irradiation, respectively. This mutual benefit effect of self-cleaning and photocatalysis was also reflected in the degradation of NO. In the first five cycles, the degradation efficiency of NO decreased by 4.74% gradually under visible light due to the adhesion of oxidation products, and most of the MWT on the coating surface was regenerated after flushing, the PCD efficiency increased by 3.71%. Furthermore, after 30 days of outdoor weathering test, the PCD efficiency of MWT coating decreased by 11.74% and 12.05% under UV and visible light, respectively, which lays a foundation for the long-term effectiveness of the MWT coating in the process of use.
In recent years, superamphiphobic coatings have been widely used in industrial transportation and environmental treatments because of their unique liquid repellency. In this study, WO3-TiO2 nanorods/SiO2 were used as the constructor of surface microstructures, and 1H,1H,2H,2H-perfluorodecyltriethoxysilane was used as the provider of low surface energy, and a photocatalytic superamphiphobic coating (FTS coating) was prepared. The microstructure and chemical composition of the coating was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The coating exhibited excellent photocatalytic activity toward degradation methyl red and nitric oxide (NO), and the degradation efficiency to NO reached 47.8%. Also, the advanced contact angle and the hysteresis angle of water, glycol, glycerol, and olive oil was used to evaluate the superamphiphobicity. After 7 days of ultraviolet (UV) aging, five cycles of airbrush flushing and 48 h of immersion in acid, salt, and alkali solutions, the FTS coating still exhibits excellent amphiphobicity, which lays a foundation for its large-scale applications in the concrete exterior wall. The surface microstructure and the formation of air pockets are a prerequisite for superamphiphobicity, which promotes the liquid on the coating surface into the Cassie-Baxter state. Furthermore, the formation of air pockets is closely related to the gas adsorption capacity and the specific surface area (SBET) of the surface microstructure on the coating surface. The coatings with different SBET constructed and the advanced contact angle were measured. The influence of air pockets on the superamphiphobicity of coatings was studied in combination with the optical microscope. The understanding that SBET further influences superamphiphobicity by affecting the surface air pockets is proposed.
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