Preparation of Ag-TiO2/Sr4Al14O25:Eu2+,Dy3+ Photocatalyst on Phosphor Beads and Its Photoreaction Characteristics
Seong-Rak Eun, Shielah Mavengere, Jung-Sik Kim
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.