Photocatalytic Properties of Layered Metal Oxides Substituted with Silver by a Molten AgNO3 Treatment
2015-07-15T00:00:00Z (GMT)
by
K4Nb6O17 (BG: 3.67 eV) and Na2W4O13 (BG: 3.12 eV) layered oxide photocatalysts
with wide band gaps were treated with a molten AgNO3 to
substitute K+ and Na+ with Ag+, resulting
in red-shifts of absorption edges in diffuse reflectance spectra.
A part of Na+ ions in the interlayer of Na2W4O13 was substituted with Ag+ ions by
the molten AgNO3 treatment with keeping the layered structure.
Both Ag(I)-substituted K4Nb6O17 and
Na2W4O13 showed photocatalytic activities
for O2 evolution from aqueous solutions containing a sacrificial
reagent utilizing the absorption bands newly formed by the Ag(I)-substitution.
Notably, the Ag(I)-substituted Na2W4O13 produced O2 under visible light irradiation. When ball-milled
Na2W4O13 was treated with a molten
AgNO3, the Ag(I)-substitution rate increased. The Ag(I)-substituted
Na2W4O13 with ball-milling showed
higher photocatalytic activity for O2 evolution than that
without ball-milling. Z-schematic water splitting proceeded under
visible light irradiation by combining the Ag(I)-substituted Na2W4O13 of an O2-evolving photocatalyst
with Ru-loaded SrTiO3 doped with Rh of a H2-evolving
photocatalyst.
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