Synthesis of transparent Ti-containing mesoporous silica thin film materials and their unique photocatalytic activity for the reduction of CO 2 with H2O

Yasushi Shioya, Keita Ikeue, Makoto Ogawa, Masakazu Anpo

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The transparent Ti-containing mesoporous silica thin film materials having two different types of hexagonal and cubic pore structures with a thickness of about 50μm and a lateral size of a few centimeters were successfully synthesized by the solvent evaporation method from tetramethoxysilane (TMOS), vinyltrimethoxysilane (VTMOS), titanium tetra(iso-propoxide) (TIP), and octadecyltrimethylammonium chloride (C18TAC). The films were converted to Ti-containing nanoporous silica thin films by subsequent calcinations in air at 823K, while the highly ordered mesostructures and macroscopic morphology were retained after the surfactant removal by calcination. The films with hexagonal and cubic symmetry were obtained by changing the composition of the starting mixtures. Various spectroscopic measurements of these films clearly showed that Ti ions are present in the silica networks as a tetrahedrally coordinated Ti-oxide species with a high dispersion state. Thus, developed transparent Ti-containing thin films were used as photocatalysts for the reduction of CO2 with H2O to evaluate their unique and high photocatalytic activity. UV irradiation of these films in the presence of CO2 and H2O led to the formation of CH4 and CH3OH as well as CO and O 2 as minor products, their yields increasing linearly against irradiation time, indicating that these films operate as efficient photocatalysts to proceed such a difficult reaction catalytically at 323K. Furthermore, the films having hexagonal pore structure exhibited higher photocatalytic activity than the Ti-MCM-41 powdered catalyst even with the same pore structure.

Original languageEnglish
Pages (from-to)251-259
Number of pages9
JournalApplied Catalysis A: General
Volume254
Issue number2
DOIs
Publication statusPublished - 2003 Nov 20

Keywords

  • Mesoporous molecular sieves
  • Photocatalysis
  • Reduction of CO with HO
  • Ti-containing thin films
  • Ti-oxide species
  • Transparent mesoporous thin films
  • XAFS measurements

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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