Investigation of photocatalytic reaction for thetitanium dioxide-phosphor composite

Abstract

The present study examined the photocatalytic reaction of titanium dioxide (TiO 2 )-coated, phosphor composite particles. Nanocrystalline TiO 2 layers were directly coated on the alkaline earth aluminate phosphor (CaAl 2 O 4 :Eu 2+ ,Nd 3+ ) particles by a sol-gel processing method and their photocatalytic reaction was analyzed according to the degradation of methylene blue aqueous solution under visible light irradiation. Compared with pure TiO 2 , the TiO 2 -coated phosphor powders showed a different photocatalytic mechanism and much faster photocatalytic reactivity under visible irradiation than that of pure TiO 2 , which was almost negligible. The mechanism of the photocatalytic reactivity for the TiO 2 -phosphor composite was discussed in terms of the energy band structure and phosphorescence. In addition, the TiO 2 -coated phosphor powders were characterized by X-ray diffraction and transmission electron microscopy.

Microwave-assisted synthesis of ZnO–Y3Al5O12:Ce3+ composites with enhanced visible light photocatalysis

“…It was found that the composites had a significantly enhanced photocatalytic activity for visible and solar light photocatalytic degradation of congo red and azo fuchsine as compared with the pure semiconductor photocatalyst. Yoon et al 33,34 prepared a CaAl 2 O 4 :Eu 2+ ,Nd 3+ -TiO 2 composite using a sol-gel process and atomic layer deposition method and investigated the photocatalytic activity in the degradation of methylene blue (MB) aqueous solution under visible light irradiation. The composite showed much higher photocatalytic reactivity than the pure TiO 2 particles.…”

Light-Storing Photocatalyst: The Possibility of Activating Titanium Dioxide by Photoluminescence

“…Recent literature (10–11–12–13–14–15–16–17–18–19–20–21) has shown that the photocatalytic activity of TiO 2 can be greatly enhanced by doping it with either metal or nonmetal ions or, possibly, both. Another way that has been investigated is the activation of titanium dioxide through the phosphorescence of an appropriate substrate (22–23–24–25). The aim of this coupling is one of the theoretical solutions to the problem of increasing the titania absorption of the solar radiation.…”

“…The whole system, usually called light-storing photocatalyst, seems to have 2 main advantages: the system absorbs a higher percentage of the incident radiation, and the phosphorescent substrate can keep the titanium dioxide active even in conditions of darkness thanks to its light emission. This improvement of absorption is achieved because the semiconductor is irradiated both by the direct light and by the luminescent substrate, which is activated at the same time, and because the absorption spectrum of TiO 2 seems to shift to a higher wavelength when it interacts with a phosphor (22–23–24).…”

“…In their work, Yoon and Kim (23) used a light-storing photocatalyzer powder similar to the one used by Li and Wang (powder of CaAl 2 O 4 : Eu,Nd mixed in a TBOT sol-gel solution and calcined). However, the behavior of the system was analyzed through the photobleaching of methylene blue (MB) aqueous solutions under visible light illumination (λ>400 nm).…”

Light converting phosphor-based photocatalytic composites

“…146,147 prepared CaAl 2 O 4 :Eu 2+ ,Nd 3+ /anatase TiO 2 , and CaAl 2 O 4 :Eu 2+ ,Nd 3+ /anatase TiO 2 /Al 2 O 3 composites using a sol-gel processing and atomic layer deposition…”