Structures, electron density and characterization of novel photocatalysts, (BaTaO2N)1−x(SrWO2N)x solid solutionsElectronic supplementary information (ESI) available: (A) Sample photos, (B) photocatalytic activity measurement details, (C) Rietveld analysis results of synchrotron X-ray diffraction data and compositional dependence of lattice parameter, (D) band gap estimation, and (E) photocatalytic activity. See DOI: 10.1039/c7dt02873c
Tungsten-modified barium tantalum oxynitride is a new visible-light photocatalyst for water oxidation. In the present work, novel barium tantalum strontium tungsten oxynitride solid solutions, (BaTaO 2 N) 1− x (SrWO 2 N) x , with a cubic Pm 3&cmb.macr; m perovskite-type structure ( x = 0.01 and...
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Main Authors | , , , , |
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Format | Journal Article |
Language | English |
Published |
07.11.2017
|
Online Access | Get full text |
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Summary: | Tungsten-modified barium tantalum oxynitride is a new visible-light photocatalyst for water oxidation. In the present work, novel barium tantalum strontium tungsten oxynitride solid solutions, (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
, with a cubic
Pm
3&cmb.macr;
m
perovskite-type structure (
x
= 0.01 and 0.02) have been prepared by heating oxide precursors under an ammonia flow. These (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
catalysts exhibited photocatalytic water oxidation activity under visible light irradiation. The crystal structure, electron-density distribution, and optical properties of (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
(
x
= 0, 0.01, and 0.02) have been studied using synchrotron X-ray powder diffraction, Rietveld analysis, the maximum-entropy method (MEM), and UV-Vis reflectance measurements. The lattice parameters of (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
decreased linearly with increasing SrWO
2
N content
x
. The minimum electron density (
MED
) at the (Ta,W)-(O,N) bond, determined by the MEM analysis of (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
, increased with
x
, as supported by DFT-based calculations. These results indicate the formation of (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
solid solutions and enhanced covalent bonding due to the stronger W-N bond. The
MED
of the (Ta,W)-(O,N) bond was higher than that of (Ba,Sr)-(O,N), indicating that the (Ta,W)-(O,N) bond is more covalent. The presence of nitrogen in (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
was confirmed by the occupancy factor refined using neutron diffraction data and by the weight gain observed by thermogravimetric analysis in air. UV-Vis reflectance spectra and DFT calculations indicated that (BaTaO
2
N)
1−
x
(SrWO
2
N)
x
contains W
5+
cations with a [Xe] 4f
14
5d
1
electron configuration and exhibits a more n-type semiconducting character compared with BaTaO
2
N, which could improve the photocatalytic water oxidation activity under visible-light irradiation.
W
5+
doping in BaTaO
2
N enhances (Ta,W)-(O,N) covalent bonding and can improve the photocatalytic activity. |
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Bibliography: | Electronic supplementary information (ESI) available: (A) Sample photos, (B) photocatalytic activity measurement details, (C) Rietveld analysis results of synchrotron X-ray diffraction data and compositional dependence of lattice parameter, (D) band gap estimation, and (E) photocatalytic activity. See DOI 10.1039/c7dt02873c |
ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/c7dt02873c |