Control of silica shell thickness and microporosity of titania-silica core-shell type nanoparticles to depress the photocatalytic activity of titania

Ahmed Mohamed El-Toni, Shu Yin, Tsugio Sato

Research output: Contribution to journalArticlepeer-review

72 Citations (Scopus)

Abstract

Titania is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products because of its excellent UV light absorption properties. Its high photocatalytic activity, however, facilitates the generation of reactive oxygen species, which can oxidize and degrade other ingredients during its formulation, raising safety concerns. Dense coating of titania nanoparticles with a silica layer could help in depression of their photocatalytic activity by disturbing the formation of radicals produced by the reaction of oxygen and/or water with the electron-hole pair. Depression of the high photocatalytic activity of titania necessitates that the silica shell has to be thick, with minimum microporosity. Coating parameters were optimized to attain greater amounts of precipitated silica and thicker shells with lower microporosity, which in turn resulted in great depression of photocatalytic activity. Silica-coated titania nanoparticles were characterized by TEM, XPS, FT-IR, EDX, and microporosity measurements. The photocatalytic activity was evaluated for the coated powder to investigate the efficiency of the silica coating as well.

Original languageEnglish
Pages (from-to)123-130
Number of pages8
JournalJournal of Colloid And Interface Science
Volume300
Issue number1
DOIs
Publication statusPublished - 2006 Aug 1

Keywords

  • Photocatalytic activity
  • Seeded polymerization
  • Silica coating
  • Titania nanoparticles

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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