Abstract
Titania is a widely used photocatalytic material possessing such advantages as low cost and high reactivity under the ultraviolet light illumination. However, the fast recombination of photoexcited charge carriers limits its application. Herein, we have synthesized original nanomaterials with mosaic structures that exhibited well-defined heterojunctions and new properties. Using SEM, XRD, EPR spectroscopy, photocatalytic measurements, and photoinduced pathphysiological activity of these photocatalysts, we studied the processes of charge carrier accumulation in TiO2/MoO3, TiO2/WO3, and TiO2/V2O5 under in situ UV illumination with emphasis on the charge exchange between energy levels of these nanosized semiconductors. It is shown that the accumulation of photoinduced charges occurs in two forms (i) filled electron traps corresponding to Ti4+/Ti3+ levels and (ii) Mo5+ centers, both forms contributing to the photoinduced biocide activity of the samples. This work demonstrates that light exposure of heterostructure photocatalysts with mosaic surfaces produces different types of charge-trapping centers capable of interacting with molecular oxygen yielding peroxo species, which provide long-life light-induced ”self-cleaning” behavior. Such photoaccumulating materials open new opportunities in developing light-driven self-sterilization structures exhibiting a prolonged bactericidal effect up to 10 h after stopping light exposure.
Highlights
Numerous photocatalysts have been synthesized and tested during the last 30 years, e.g., [1,2,3,4,5,6,7,8,9]and references therein
The photoinduced redox transformations responsible for charge storage in these photocatalytic systems are based on the light-induced charge carrier separation using composites of two and three different metal oxides, which are accompanied by the generation of paramagnetic centers that makes the electron paramagnetic resonance (EPR) spectroscopy a powerful tool for the investigation of the mechanism of such processes, as well as the features of photoaccumulation effects
We used the SEM, XRD, EPR spectroscopy, photocatalytic measurements, and photoinduced pathphysiological activity of photocatalysts to elucidate the structure of energy levels involved in the storage of the reductive energy in TiO2 /MoO3 (WO3, V2 O5 ) heterostructure photocatalysts under in situ UV light illumination with emphasis on the charge exchange between these levels of different nanosized oxide semiconductors
Summary
Numerous photocatalysts have been synthesized and tested during the last 30 years, e.g., [1,2,3,4,5,6,7,8,9]. The photoinduced redox transformations responsible for charge storage in these photocatalytic systems are based on the light-induced charge carrier separation using composites of two and three different metal oxides, which are accompanied by the generation of paramagnetic centers that makes the electron paramagnetic resonance (EPR) spectroscopy a powerful tool for the investigation of the mechanism of such processes, as well as the features of photoaccumulation effects. We used the SEM, XRD, EPR spectroscopy, photocatalytic measurements, and photoinduced pathphysiological activity of photocatalysts to elucidate the structure of energy levels involved in the storage of the reductive energy in TiO2 /MoO3 (WO3 , V2 O5 ) heterostructure photocatalysts under in situ UV light illumination with emphasis on the charge exchange between these levels of different nanosized oxide semiconductors
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