Abstract
Long-lasting Sr4Al14O25:Eu2+,Dy3+ phosphor beads were prepared with inorganic sodium silicate binders and coated to support Ag-doped TiO2 catalyst by the sol–gel coating method. Energy dispersive spectroscopy and X-ray photoelectron spectroscopy confirmed that Ag and TiO2 were loaded on the bead surface. Photocatalytic degradation of toluene volatile organic compound was evaluated under ultraviolet and visible light through 410 nm filters. The photocatalyst/phosphor beads of Ag-TiO2/Sr4Al14O25:Eu2+,Dy3+ decorated with 0.035 M Ag in N2 and N2-H2 atmospheres exhibited higher photocatalytic efficiencies compared with beads heat treated in air. A low amount of Ag impregnation and the reducing atmosphere of N2/N2-H2 were beneficial for enhancing photocatalytic efficiency because Ag-doping in TiO2 imparted low energy levels for visible light sensitization. The synthesized powder-free beads possess compressive strength for possible applications, and easy recovery of the photocatalysts is beneficial for preventing any secondary pollution of nano-powders.
Highlights
Its Photoreaction Characteristics.Titanium dioxide (TiO2 ) nanoparticles (NPs) are photoactive to combat air and water pollutants under ultraviolet (UV) activation
X-ray diffraction spectra (XRD) of 0.035 M Ag-TiO2 /phosphor is shown in Figure 1 as compared to Joint Committee on Powder Diffraction Standards (JCPDS) cards for (a)
Only the peak at 27.0◦ is referenced to TiO2 rutile JCPDS 75-1753
Summary
Its Photoreaction Characteristics.Titanium dioxide (TiO2 ) nanoparticles (NPs) are photoactive to combat air and water pollutants under ultraviolet (UV) activation. Several studies have been conducted to enable the sensitization of visible light by TiO2 NP [1]. The prevalent approaches for extending TiO2 absorption edge are doping with metals/non-metals [2,3] and coupling with metal oxides [4] or noble metals [5,6]. The effect of coupling 3-composites was studied and reported to show that TiO2 forms heterojunctions in the presence of coupling. One of the cost-effective practical techniques of doping and coupling TiO2 is the wet process method. The disadvantage of coupling two or more NP composites is uncontrollable agglomeration in wet processes. This results in the incorporated phases being dominant and even deterioration of photocatalytic efficiencies
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