Preparation of 3-D ordered macroporous tungsten oxides and nano-crystalline particulate tungsten oxides using a colloidal crystal template method, and their structural characterization and application as photocatalysts under visible light irradiation

Masahiro Sadakane, Keisuke Sasaki, Hironobu Kunioku, Bunsho Ohtani, Ryu Abe, Wataru Ueda

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Abstract

Three-dimensionally ordered macroporous (3DOM) tungsten(vi) oxide (WO 3) was prepared using a colloidal crystal template method. Well-ordered 3DOM WO3 was prepared with a high pore fraction using ammonium metatungstate ((NH4)6H2W 12O40), a Keggin-type dodecatungstate, as a tungsten precursor; WO3 materials prepared by other commercially available W precursors, tungsten chloride (WCl6), tungsten(v) ethoxide (W(OEt)5), and phosphotungstic acid (H3PW 12O40), have a low 3DOM pore fraction. These WO 3 materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), powder X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET) analysis of nitrogen adsorption isotherm, and Raman spectroscopy. Non-porous WO3 prepared from ammonium metatungstate without a poly(methyl metacrylate) (PMMA) template grew to crystal sizes of up to several micrometres with a low specific surface area (ca. 1-2 m2 g-1). In the presence of a colloidal crystal template of PMMA spheres, WO3 crystal grew in the nanometre-sized voids between the PMMA spheres, and the specific surface area thus increased up to ca. 30 times compared to non-porous WO3. The surface area is tunable by changing the PMMA sphere diameter. Calcination of the 3DOM WO 3 produced WO3 nano-crystalline particles by sintering-induced disassembly. After Pt-loading, these WO3 materials showed higher photocatalytic activity compared to non-porous WO3 for decomposition of acetic acid in air under visible light irradiation.

Original languageEnglish
Pages (from-to)1811-1818
Number of pages8
JournalJournal of Materials Chemistry
Volume20
Issue number9
DOIs
Publication statusPublished - 2010
Externally publishedYes

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