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Due to the semi-closed structure of the tunnel, serious air pollution in tunnels from vehicle exhaust becomes an issue which needed to be addressed. Among the exhaust, nitric oxide (NO) is typically considered as one of the main pollutants. In this paper, a superhydrophobic photocatalytic coating was fabricated by a spraying method by airbrush with a WO3/TiO2 photocatalysis for NO degradation. The water advanced contact angle (WACA) of the coating reached 166.32°, and the WACA was still above 145° after the 30 times abrasion test. The coating exhibited an excellent ability to remove inorganic and organic pollutants. Also, the NO degradation efficiency of this superhydrophobic coating under ultraviolet and visible light sources and humid environments was tested. When the relative humidity reached 98%, the NO degradation efficiency of the coating remained unchanged under visible light irradiation compared with the relative humidity of 45%. In addition, the coating exhibited prominent stability of NO degradation during the cyclic test. Furthermore, the WT coating showed stability and synergy of self-cleaning and photocatalysis toward NO degradation, which ensured the long-term use of the coating. Finally, a synergistic mechanism for self-cleaning and photocatalysis was proposed. This may provide a new idea and support for the application of photocatalytic technology in the degradation of NO in the tunnel. [ABSTRACT FROM AUTHOR]

[Display omitted] • A self-cleaning synergistic photocatalytic superamphiphobic coating. • The inhibition of NO 2 production during the NO photocatalytic degradation process. • Synergistic effect of self-cleaning and photocatalysis of photocatalytic coating. • A green NO photocatalytic degradation mechanism of photocatalytic coating. Multitudinous deleterious NO 2 will be produced in the process of NO photocatalytic degradation, which may cause serious secondary pollution. In this study, a self-cleaning synergistic photocatalytic coating was constructed by the simple spray method. The coating has excellent superamphiphobicity and NO degradation performance. In addition, the production of NO 2 in the process of NO degradation by photocatalytic superamphiphobic coating was inhibited, which indicated the greener photocatalytic process exhibited by this photocatalytic coating. Also, to clarify the inhibition of the coating on NO 2 , the NO degradation mechanism of the coating and photocatalyst was investigated by in situ IR, trapping test and EPR spectra, and the possible pathway of NO degradation was summarized. Combining the result of DFT calculation and degradation product analysis, the inhibition of NO 2 and"green" degradation mechanism of the self-cleaning synergistic photocatalytic coating was explored and proposed, which may provide some theoretical support for the "green" application of photocatalysis. [ABSTRACT FROM AUTHOR]

Photocatalytic coating has been widely studied as a promising material to remove air pollutants. However, the effectiveness and long-term effect of photocatalysis in high relative humidity environment is still the main challenge in this field. In this study, a fluorinated WO 3 -TiO 2 nanorods/SiO 2 epoxy photocatalytic superamphiphobic coating (FTSE coating) was prepared using a simple spraying method. The micromorphology and chemical composition of FTSE coating was characterized by SEM, EDS, FT-IR, XPS and TGA techniques. The advanced contact angle and hysteresis angle test show that the FTSE coating had excellent superamphiphobicity. The mechanical abrasions, corrosion resistance and UV aging tests show that the FTSE coating exhibited reasonable durability. Besides, the NO degradation efficiency of hydrophilic and superamphiphobic coatings with contact angles of 20.19°, 87.74°, 162.93° and 164.47° was tested in different humidity environment. The results showed that the superamphiphobic coating exhibited more superior photocatalytic degradation efficiency (84.02%) than the hydrophilic coating (51.38%) at a high relative humidity (RH=98%). Finally, FTSE coating exhibited prominent photocatalytic stability and the synergistic effect of photocatalysis and self-cleaning. After 30 d outdoor weathering test, the NO degradation efficiency decreased by 13.07% and recovered to the original level after flushing. The improvement mechanism of NO degradation performance was proposed based on the characteristics of superamphiphobic surface. [Display omitted] • A WO 3 -TiO 2 nanorods/SiO 2 photocatalytic superamphiphobic coating. • The reasonable robustness and excellent superamphiphobicity. • The prominent degradation performance in high relative humidity environment. • A mechanism of improving the NO degradation efficiency. [ABSTRACT FROM AUTHOR]