A visible-light-sensitive Bi₂MoO₆–BiOCl heterojunction photocatalyst was synthesized via a hydrothermal process.

TiO₂ sol was produced by the sol-gel method through the hydrolysis and the aging of tetrabutyl titanate and the TiO₂ film was obtained by dipping and uniform lifting of the acid-treated and ultrasound-treated clean glass slides into the TiO₂ sol followed by aging, drying, and calcination. The effect of the hydrolysis control agents to the formed sol was researched and the crystalline state, the morphology, and the photocatalytic properties of the products after calcination were characterized. The structural morphology, the contact angles before and after illumination, and the self-cleaning properties of the TiO₂ film were characterized as well. The results showed that by using acetylacetone as the hydrolysis control agent, the formed TiO₂ sol had relatively high stability. The product after the calcination of the TiO₂ sol was of single anatase type with crystalline size of 18–20 nm and it could degrade nearly 100% of methylene blue after 90 min illumination. The formed TiO₂ film is compact, continuous, smooth, and had the properties of super-hydrophilicity (after 30 min illumination due to its contact angle decreasing from 21° to nearly 0°) and anti-fogging capability, which indicated its excellent self-cleaning property.

A photocatalytic active CdS-TiO₂ heterostructure composite was prepared by hydrothermal method and its morphology and properties were characterized. Results indicate that the CdS nanoparticles deposited on the surface of a TiO₂ nanoparticles, which was in anatase phase. The particle scale of both of the components reached approximately 15 nm. In comparison to pure TiO₂ (410 nm), the light absorption edge of the heterostructure composite was 550 nm, which could extend the light response from UV to the visible region. Under visible light irradiation, the degradation efficiency of tetracycline hydrochloride by the CdS-TiO₂ composite achieved 87.06%, significantly enhancing photocatalytic activity than the as-prepared pure TiO₂ and commercial TiO₂ (Degussa P25). This character is attributed to the synergetic effect of these two components in the absorption of visible light.

In order to improve the dispersion of nano-TiO₂ particles and enhance its self-cleaning properties, including photocatalytic degradation of pollutants and surface hydrophilicity, we prepared nano-TiO₂-coated SiO₂ microsphere composite self-cleaning materials (SiO₂–TiO₂) by co-grinding SiO₂ microspheres and TiO₂ soliquid and calcining the ground product. The structure, morphology, and self-cleaning properties of the SiO₂–TiO₂ were characterized. The characterization results showed that the degradation efficiency of methyl orange by SiO₂–TiO₂ was 97%, which was significantly higher than that obtained by pure nano-TiO₂. The minimum water contact angle of SiO₂–TiO₂ was 8°, indicating strong hydrophilicity and the good self-cleaning effect. The as-prepared SiO₂–TiO₂ was characterized by the nano-TiO₂ particles uniformly coated on the SiO₂ microspheres and distributed in the gap among the microspheres. The nano-TiO₂ particles were in an anatase phase with the particle size of 15–20 nm. The nano-TiO₂ particles were combined with SiO₂ microspheres via the dehydroxylation of hydroxyl groups on their surfaces.

CaCO₃-TiO₂ composite particles were prepared with calcium carbonate (CaCO₃) and TiO₂ in stirred mill according the wet grinding method. The pigment properties, morphology, and structure of CaCO₃-TiO₂ composite particles and the interaction behaviors between CaCO₃ and TiO₂ particles were explored. In the CaCO₃-TiO₂ composite particles, TiO₂ is uniformly coated on the surface of CaCO₃ and the firm combination between CaCO₃ and TiO₂ particles is induced by the dehydration reaction of surface hydroxyl groups. CaCO₃-TiO₂ composite particles have similar pigment properties to pure TiO₂. The hiding power, oil absorption, whiteness and ultraviolet light absorption of composite particles are close to those of pure TiO₂. The application performance of CaCO₃-TiO₂ composite particles in the paint is consonant with their pigment properties. The contrast ratio of the exterior paint containing CaCO₃-TiO₂ composite particles is equivalent to that of the paint containing the same proportion of pure TiO₂.