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Issue 34, 2012
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Structural and photocatalytic properties of perovskite-type (La,Ca)Ti(O,N)3 prepared from A-site deficient precursors

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Abstract

Two series of oxide precursors for perovskite-type (La,Ca)Ti(O,N)3 were prepared by adding Ca2+ to A-site deficient LaTiO3.5 heterogeneously (Ca2+-backfilling) or by substituting Ca2+ for La3+ in stoichiometric LaTiO3.5 homogeneously (Ca2+-substitution). Activity of the resultant (La,Ca)Ti(O,N)3 for photocatalytic O2 evolution was tested in the presence of an electron acceptor (Ag+) and a superior activity of Ca2+-backfilled LaTiO2N compared to Ca2+-substituted LaTiO2N and unsubstituted LaTiO2N was demonstrated. X-ray diffraction patterns of the precursor oxides revealed a higher degree of crystallinity in La1−xTiO3.5−3x/2 compared to La1−xCaxTiO3.5−x/2. The higher crystallinity in La1−xTiO3.5−3x/2 resulted in lower Ti3+ defect formation during the ammonolysis reaction. This was evidenced by the lower background absorption of the diffuse reflectance spectra in Ca2+-backfilled compared to Ca2+-substituted LaTiO2N. Structural refinement of the diffraction patterns revealed growing crystal sizes with the Ca2+ content, which was more pronounced for Ca2+-backfilled than for Ca2+-substituted LaTiO2N. Thus, the enhanced photocatalytic activity of Ca2+-backfilled LaTiO2N was related to the quality of the precursor oxides, which influenced the defect concentrations and crystallite sizes of the resulting oxynitrides.

Graphical abstract: Structural and photocatalytic properties of perovskite-type (La,Ca)Ti(O,N)3 prepared from A-site deficient precursors

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Article information


Submitted
30 Apr 2012
Accepted
09 Jul 2012
First published
26 Jul 2012

J. Mater. Chem., 2012,22, 17906-17913
Article type
Paper

Structural and photocatalytic properties of perovskite-type (La,Ca)Ti(O,N)3 prepared from A-site deficient precursors

A. E. Maegli, T. Hisatomi, E. H. Otal, S. Yoon, S. Pokrant, M. Grätzel and A. Weidenkaff, J. Mater. Chem., 2012, 22, 17906
DOI: 10.1039/C2JM32718J

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