Статья

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

Alexandra E. MaegliEMPA – Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf, SwitzerlandTakashi HisatomiEPFL – École Polytechnique Fédérale de Lausanne, Laboratory of Photonics and Interfaces, CH-1015 Lausanne, SwitzerlandEugenio H. OtalEMPA – Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf, SwitzerlandSonghak YoonEMPA – Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf, SwitzerlandSimone PokrantEMPA – Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf, SwitzerlandMichaël GrätzelEPFL – École Polytechnique Fédérale de Lausanne, Laboratory of Photonics and Interfaces, CH-1015 Lausanne, SwitzerlandAnke WeidenkaffEMPA – Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf, Switzerland

2012en

ABI

Аннотация

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.

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Идентификаторы

DOI: 10.1039/c2jm32718j

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