10.1002/cssc.201700615
ChemSusChem
FULL PAPER
thoroughly with ethanol and distilled water and dried overnight in air at
80 °C. The dried product was calcined at 700 °C in air for 3h.
Laser irradiation of 785 nm was used for the excitation. Silicon was used
as a standard for the calibration of Raman shifts.
For preparation SrSnO3 by Ionothermal synthesis, the experiment was
achieved in 50 ml Teflon© cup enclosed in stanless steel autoclaves (parr
Instrument, USA). The reaction mixture was transferred to the Teflon© cup,
and sealed in the autoclave, which was put in a furnace where it was
Photocatalytic activity test
Photo-hydroxylation of terephthalic acid (TA). The catalytic test was
performed in a reactor, which contained a suspension of 100 mg
photocatalyst in 100 ml of 0.01 M NaOH solution containing 3 mM
terephthalic acid (C8H6O4). The suspension was continuously stirred in the
dark for 30 minutes to establish the adsorption/desorption equilibrium, and
then illuminated using a 100 W Xe arc lamp (Newport Oriel Instruments).
The lamp was switched on 30 min prior to the illumination of the samples
in order to stabilize the power of its emission at λ > 320 nm (a cut-off filter
FSQ-WG320 was used to eliminate most of the radiation below 320 nm).
Every 30 min about 3 ml aliquots were sampled and filtered through nylon
syringe filters (pore size 0.2 μm) to remove the photocatalyst before
analysis by fluorescence spectrometry monitoring at 426 nm
corresponding to the fluorescence band of 2-hydroxy terephthalic acid
(TAOH) as photogenerated holes can react with surface adsorbed water
forming .OH radicals which react with terephthalic acid to compose 2-
hydroxy terephthalic acid, that exhibits a typical fluorescence band at 426
nm once an excitation wavelength at 320 nm is applied. Thus an increase
in intensity with time is directly linked to an increased amount of
photogenerated .OH radicals.
heated at 170 ̊C for 20 h. Then, the autoclave was cooled in air. The
resulting powder was separated by centrifugation, washed with ethanol
and deionizes water several times, and dried at 80 °C overnight. The dried
product was calcined at 700 °C in air for 3h.
Characterization
Powder X-ray diffraction (PXRD). Powder X-ray diffraction
measurements were carried out on a PANalytical powder diffractometer
with a Xcelerator Detector employing CuKα radiation (λ = 0.15406 nm).
The structure parameters were determined by Rietveld refinment with the
Fullprof program suite using a pseudo-Voigt peak shape function. [46]
X-ray photoelectron spectroscopy (XPS). XPS measurements
were done on a physical electronic 5500 multitechnique system with
standard an aluminium source. Analysis spot size was 1x1 mm. Samples
were mounted on double sided Scotch© tape. The binding energies in the
XPS spectra are calibrated against the C1s signal (284.8 eV)
corresponding to adventitious physisorbed carbon oxide.
Keywords: Alkaline earth stannates • Perovskite • Nanocrystal •
Ionic liquid • photocatalyst
Scanning electron microscopy (SEM). Scanning electron
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microscopy measurements were performed with
a high resolution
thermally aided field SEM (Zeiss, LEO 1530 Gemini) with a field emission
gun (FEG) and an acceleration voltage of Uacc = 0.2-30 KV. For the SEM
measurements the Sr1-xBaxSnO3 powders were put on a carbon-film,
dried under vacuum for 20 min.
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Surface area. Nitrogen physisorption experiments were carried out at 78
K in a Micromeritics Tristar analyzer. The sample was thermally pretreated
at 100 °C for 6 h under flowing N2. The surface area is calculated
according to the BET (Brunauer-Emmett-Teller) method.
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UV-vis spectroscopy. UV-Vis spectra were measured at room
temperature in reflection mode on an Agilent Cary 60 spectrometer using
a dip probe coupler (Agilent) and a VideoBarrelino (Harrick).
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Fluorescence spectroscopy. PL spectra were measured on a
Agilent Technologies Cary Eclipse Fluorescence Spectrophotometer
equipped with a Xenon flash lamp and build-in excitation and emission
filters. For the measurment, liquid samples were filled into a standard 10
mm quartz cuvette and positioned in the incoming beam in the sample
chamber.
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IR spectroscopy. Attenuated total reflection (ATR) spectroscopy was
carried out on an Agilent Technologies Cary 630 FT-IR spectrometer
equipped with a diamond crystal ATR unit. Solid samples were pressed on
the crystal.
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Raman spectroscopy. Raman spectra were obtained at 150 mW on a
Horiba Xplora Raman microscope (Horiba Scientific) at room temperature.
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