Photoreactivity improvement of TiO2/Sr4All4O25:Eu,Dy heterojunction photocatalyst by Fe doping and annealing in N2–H2 mixed gas

Shielah Mavengere, Jung Sik Kim

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Sr4All4O25:Eu,Dy phosphor beads were impregnated with Fe, followed by TiO2 sol–gel coating. The heat treatment atmospheres after TiO2 coating were N2, N2–H2 mixed gas, and air. X-ray diffraction, scanning electron microscopy, and energy dispersive analysis confirmed the crystallinity, spherical nano-TiO2 morphology, and elemental composition of the Fe-doped TiO2/Sr4All4O25:Eu,Dy phosphor beads. X-ray photoelectron spectroscopy analysis verified the existence of oxygen-deficient Tiδ+ due to the Fe doping and reducing atmosphere. Additionally, the thermal treatment of Sr4Al14O25:Eu,Dy/TiO2 beads in the N2–H2 reducing atmosphere enhanced N doping in the TiO2 matrix. The red shift of the diffuse absorption spectra increased with the amount of Fe doped on phosphor, indicating heterojunction narrowing in Sr4Al14O25:Eu,Dy/Fe-TiO2. Photoluminescence emission deteriorated with increasing Fe doping and N2 heat treatment. However, the N2–H2 mixed gas preserved up to 90% of the photoluminescence intensities regardless of the amount of Fe dopant on the phosphor/TiO2 bead surface. The photoreactivity performance was evaluated using a toluene volatile organic compound as pollutant under 30 lx ultraviolet (UV) and 1200 lx visible light sources. The 0.06 M Fe-impregnated Sr4Al14O25:Eu,Dy/TiO2 beads heat treated in a N2–H2 reducing atmosphere exhibited outstanding photocatalytic activity of up to above 95% for 60 min in both UV and visible light activated reactions. Moreover, the 0.06 M Fe-doped Sr4Al14O25:Eu,Dy/TiO2 phosphor beads demonstrated plausible reusability with photocatalytic efficiencies above 90% in five repeated test cycles.

Original languageEnglish
Pages (from-to)3387-3398
Number of pages12
JournalApplied Nanoscience (Switzerland)
Volume12
Issue number11
DOIs
StatePublished - Nov 2022

Keywords

  • Fe doping
  • SrAlO:Eu,Dy long-lasting phosphor
  • TiO
  • TiO/SrAlO:Eu,Dy photocatalyst
  • UV–Vis photocatalysis

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