A new approach has been developed for the fabrication of visible light photocatalysts. Nanoclusters of
MoS2 and WS2 are coupled to TiO2 by an in situ photoreduction deposition method taking advantage of
the reducing power of the photogenerated electrons from TiO2 particles. The photocatalytic degradation
of methylene blue and 4-chlorophenol in aqueous suspension has been employed to evaluate the visible
light photocatalytic activity of the powders. The blue shift in the absorption onset confirms the size
quantization of MS2 nanoclusters, which act as effective and stable sensitizers, making it possible to utilize
visible light in photocatalysis. Quantum size effects alter the energy levels of the conduction and valence
band edges in the coupled semiconductor systems, which favors the interparticle electron transfer. In
addition, the coupled systems are believed to act in a cooperative manner by increasing the degree of charge
carrier separation, which effectively reduces recombination.
Transparent TiO2 films on stainless steel prepared by dip coating in a nonionic microemulsions solution have been shown to have much higher photocatalytic activity than those coatings on glass. Fe3+ and Fe2+ ions, diffusing from stainless steel substrate into TiO2 films during high-temperature calcination, behave as dopants to significantly affect the films' photocatalytic activity. An optimum calcination condition, under which the amount of diffused Fe3+ and the ratio of Fe3+ to Fe2+ ions favor the film's photocatalytic reaction, was obtained. In addition, this TiO2 films also exhibits excellent photoinduced hydrophilicity and antibacterial effect for the sterilization of Bacillus pumilus. As stainless steel is a very common material, practical systems for pollution treatment and disinfection may be designed based on this enhanced coating.
ZnWO4 photocatalysts with various morphologies were synthesized by a hydrothermal process. The effects of
hydrothermal temperature and time on the crystallinity and morphology of ZnWO4 catalyst were investigated. The
crystallinity was enhanced with the increase of hydrothermal temperature and hydrothermal time. The formation of
ZnWO4 nanoparticles was controlled via kinetic process above 160 °C, and ZnWO4 nanorods with a highly [100]-preferred orientation formed via the thermodynamically control process in the temperature range of 120−140 °C.
The morphology and crystallinity of ZnWO4 photocatalyst have a significant influence on the photocatalytic activity
for aqueous Rhodamine B and gaseous formaldehyde degradation. ZnWO4 nanorod catalyst showed a much higher
photocatalytic activity than the nanoparticle one. The enhanced photocatalytic activity can be attributed to the
anisotropic structure of nanorod.
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