UV–visible light photocatalytic properties of NaYF 4 :(Gd, Si)/TiO 2 composites

Shielah Mavengere, Jung Sik Kim

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

In this study, a new novel composite photocatalyst of NaYF 4 :(Gd, Si)/TiO 2 phosphor has been synthesized by two step method of solution combustion and sol-gel. The photocatalyst powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–vis spectroscopy and photoluminescence (PL) spectroscopy. Raman spectroscopy confirmed the anatase TiO 2 phase which remarkably increased with existence of yttrium silicate compounds between 800 cm −1 and 900 cm −1 . Double-addition of Gd 3+ -Si 4+ ions in NaYF 4 host introduced sub-energy band levels with intense absorption in the ultraviolet (UV) light region. Photocatalytic activity was examined by exposing methylene blue (MB) solutions mixed with photocatalyst powders to 254 nm UV-C fluorescent lamp and 200 W visible lights. The UV and visible photocatalytic reactivity of the NaYF 4 :(Gd, 1% Si)/TiO 2 phosphor composites showed enhanced MB degradation efficiency. The coating of NaYF 4 :(Gd, 1% Si) phosphor with TiO 2 nanoparticles creates energy band bending at the phosphor/TiO 2 interfaces. Thus, these composites exhibited enhanced absorption of UV/visible light and the separation of electron and hole pairs for efficient photocatalysis.

Original languageEnglish
Pages (from-to)491-496
Number of pages6
JournalApplied Surface Science
Volume444
DOIs
StatePublished - 30 Jun 2018

Keywords

  • Composites
  • NaYF :(Gd, Si)/TiO
  • Photocatalyst
  • UV–visible
  • Upconversion phosphor

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