Synthesis of Er3+:Y3Al5O12 and its effects on the solar light photocatalytic activity of TiO2–ZrO2 composite

Abstract

The Er 3? :Y 3 Al 5 O 12 as an upconversion luminescence agent, which can transform visible light into ultraviolet light, was synthesized by nitrate-citrate acid and calcined method. Then, a novel photocatalyst, Er 3? :Y 3 Al 5 O 12 /TiO 2 -ZrO 2 , was prepared using ultrasonic dispersion and liquid boiling method. The samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). In succession, the degradation process of organic dye was monitored by UVVis spectrum and ion chromatography for verifying the photocatalytic activity of Er 3? :Y 3 Al 5 O 12 /TiO 2 -ZrO 2 . The influences on its photocatalytic activity such as Ti/Zr molar ratio, heat-treated temperature, and time were studied. In addition, the influences of initial concentration, Er 3? :Y 3 Al 5 O 12 /TiO 2 -ZrO 2 amount, solar light irradiation time, and organic dye category on the photocatalytic degradation efficiency were also investigated. It was found the photocatalytic activity of Er is a useful photocatalytic material for the wastewater treatment duo to efficient utilization of solar light.

Hybrid Homogeneous and Heterogeneous Photocatalytic Processes for Removal of Triphenylmethane Dyes: Artificial Neural Network Modeling

“…This phenomenon enhances the probability of charge‐carrier recombination and prompts the end of the photocatalytic oxidation . With increasing the initial dye concentration, more dye molecules are adsorbed on the TiO 2 −SiO 2 surface, and consequently the chance of forming reactive species such as • OH radicals will be diminished . On the other hand, with increases in the initial concentration, the dye solution gets impermeable to UV irradiation because the molar extinction coefficient of the dyes at 254 nm (the wavelength of UV lamp) is very high.…”

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“…[66][67][68][69] Light-conversion phosphors (LCPs) including upconversion phosphors (UCPs) and down-conversion phosphors (DCPs), which transform lower (higher) energy phonons into higher (lower) energy photons, have attracted tremendous interest in recent years owing to their special electronic structure and unique properties. [70][71][72][73] Investigations have been carried out to study LCP-semiconductor composites for photocatalysis. [72][73][74][75][76][77][78] The LCPs can absorb the given energy photon and emit other energy photons, which can be easily absorbed by a given dye or effectively excite the semiconductor to generate more electron-hole pairs.…”

“…[70][71][72][73] Investigations have been carried out to study LCP-semiconductor composites for photocatalysis. [72][73][74][75][76][77][78] The LCPs can absorb the given energy photon and emit other energy photons, which can be easily absorbed by a given dye or effectively excite the semiconductor to generate more electron-hole pairs. Besides the light-converting ability, long afterglow phosphors (LAPs) as one kind of LCP can emit long lasting phosphorescence, which contributes to persistent photocatalytic performance after turning off the irradiation light.…”

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“…Therefore, the photocatalytic degradation ability of ZnO, 44 ZnO-TiO 2 , 45 Fe-doped TiO 2 -ZnO, 46 or Fe-/Co-doped TiO 2 47 could be facilitated by Er 3+ :YAlO 3 under visible light. Moreover, Er 3+ :Y 3 Al 5 O 12 as a similar upconversion phase can also enhance the photocatalytic degradation of TiO 2 -ZrO 2 48 and TiO 2 -ZnO 49 through upconversion PL processes.…”