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To reduce vehicle exhaust gas pollution in transport-intensive roadways and tunnels, six types of photocatalytic asphalt binders were designed using graphite-phase carbon nitride (g-C3N4) and nanoscale titanium dioxide (nano-TiO2) particles. In this paper, the rheological behaviors and fatigue life of the nano-TiO2-modified asphalt binder (TiO2-MA) and g-C3N4-modified asphalt binder (C3N4-MA) were investigated. NO degradation capacity of six types of photocatalytic asphalt binders was characterized under visible light conditions. The results showed that TiO2-MA had more excellent rheological behaviors and rutting resistance than C3N4-MA. In addition, 4 wt% nano-TiO2 markedly improved the rheological behaviors and rutting resistance of MA compared to other dosages. TiO2-MA exhibited higher fatigue resistance. The fatigue life of TiO2-MA with 4 wt% nano-TiO2 was increased to 234.1% at 2.5% strain and 242.5% at 5% strain, respectively, compared to base asphalt binder (BA). C3N4-MA had better NO degradation capacity than TiO2-MA. Meanwhile, the NO degradation efficiency of C3N4-MA reached 17.8% with 5 wt% g-C3N4. [ABSTRACT FROM AUTHOR]

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]

• A self-cleaning photocatalytic WO 3 -TiO 2 nanorod/PDMS coating. • The mutual benefit effect of self-cleaning and photocatalysis. • Visible-response photocatalytic NO degradation and self-cleaning performance. • The durable superhydrophobicity for external building wall. 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. [ABSTRACT FROM AUTHOR]

[Display omitted] Improving the separation efficiency of photo-generated charge carriers is an important strategy to enhance the photocatalytic performance. In this paper, the NaNbO 3 /WO 3 composite photocatalyst was prepared via a hydrothermal method, which exhibited a substantial increase in photocatalytic activity through the synergetic effect of visible light irradiation and ultrasound vibration. The XRD, FT-IR, Raman, SEM, XPS, UV–vis DRS, and photoluminescence spectroscopy results indicated that a large number of WO 3 particles were tightly attached to the surface of NaNbO 3 nanowires in the NaNbO 3 /WO 3 composite catalyst. Under the piezo-photocatalysis condition, the degradation efficiency of Rhodamine B (RhB) by 5 % NaNbO 3 /WO 3 was significantly improved, reaching 73.7 % within 120 min. Meanwhile, the piezo-photocatalytic degradation efficiency of the NaNbO 3 /WO 3 composite catalyst was increased by 30.1 % compared to single photocatalysis, and the corresponding reaction rate constant (K) was 2.23 times than that of single photocatalysis. In addition, quenching tests showed that h+ was the primary active species in piezo-photocatalytic process. The significant enhancement of piezo-photocatalytic performance was attributed to the piezoelectric field caused by the bending deformation of the NaNbO 3 nanowires, which was an important driving force for photo-generated charge carrier separation. Furthermore, the production of multiple redox active sites simultaneously improved the photocatalytic performance. [ABSTRACT FROM AUTHOR]

• A nitric oxide removal coating was constructed by loading doped TiO 2 /AC photocatalyst on waterborne acrylic coating. • Under visible light irradiation, the NO degradation efficiency of doped TiO 2 /AC coating was 45.8 % in 2 h, and only decreased by 5.8 % after 5 cycles. • UV stability of doped TiO 2 /AC coating was investigated, and the mechanism of improving UV stability was proposed. • After 42 d UV aging and single water flushing, the NO removal efficiency of doped TiO 2 /AC coating still reached 36.7 % and exhibited excellent UV stability. Based on the porous structure of activated carbon (AC) and the photo-oxidation behavior of TiO2, a visible-light-responsive photocatalytic coating with UV stability was constructed by loading Fe/N/Co-TiO2@AC (DTC) on waterborne acrylic coating. The DTC with adsorption and degradation synergistic effect was prepared by a simple mechanochemistry method and characterized by UV–vis, SEM, XRD, and BET. The nitric oxide (NO) removal efficiency of DTC was 51.6 % under visible light in 2 h. Besides, under the same conditions, the NO removal efficiency of the DTC coating still reached 45.8 %. Further, to investigate the UV stability of DTC coating, different coatings were prepared with the same dosage of DTC, TiO 2 @AC (TC), and TiO 2. The UV stability of the coatings was tested with a color difference, degree of chalking, adhesion strength, hardness, and impact resistance as evaluation indicators. The results showed that the DTC coating exhibited the best UV stability. The photooxidation of organic binder on the coating surface before and after aging was micro-characterized by SEM and FT-IR, and the UV stability improvement mechanism was revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] • g-C 3 N 4 nanosheets were prepared via a molten salts method. • Crystalline g-C 3 N 4 nanosheets was composed of triazine ring unit. • The g-C 3 N 4 nanosheets show the excellent photocatalytic activity for the degradation of RhB. The crystalline g-C 3 N 4 nanosheets have been successfully prepared by one-step molten salts method. The microstructures and optical properties of as-prepared samples were characterized by different techniques, such as XRD, EDS, XPS, SEM, TEM, BET, PL and Uv–vis DRS. The results showed that the unit of the crystalline g-C 3 N 4 nanosheets was composed of triazine ring, which was different from heptazine-based g-C 3 N 4. The crystalline g-C 3 N 4 nanosheets were thin and transparent, which were similar to graphene. The crystalline g-C 3 N 4 nanosheets exhibits the excellent photocatalytic activity, which can degrade 98% RhB within 120 min under visible light irradiation. However, the degradation efficiency of bulk g-C 3 N 4 is only 40% within 120 min. The enhanced photocatalytic activity of g-C 3 N 4 nanosheets can be attributed to 2D nanosheet morphology, which inhibits the electron-hole recombination. In addition, the high specific surface area of g-C 3 N 4 nanosheets positively increases the contact area with pollutants, making the degradation reaction more efficiently. A plausible photocatalytic mechanism was proposed for the degradation of RhB under visible light irradiation. [ABSTRACT FROM AUTHOR]