研究目的
To develop a novel method to obtain highly active catalysts for photocatalytic hydrogen evolution by synthesizing oxygen vacancy-rich anatase TiO2 hollow spheres through a facile preannealing-quenching strategy.
研究成果
The rapid quenching in liquid-nitrogen enhanced the photocatalytic performance of TiO2 spheres, especially for the sample with hollow structures. The sample of QH-500 exhibited a robust stability and the most excellent photocatalytic performance of hydrogen evolution (1240.5 μmol) over other quenched samples and showed 1.52 times higher performance than that of NH-500 (821.1 μmol). The enhanced photocatalytic performance, excellent stability together with facile procedure made the liquid-nitrogen quenching method having promising prospect for photocatalytic water splitting.
研究不足
The quenching process had an obvious effect on the TiO2 hollow spheres only when the preannealing temperature was below 700 oC. The oxygen vacancies on the rutile surface were not so stable and the surface oxygen vacancies would be oxidized by air again.
1：Experimental Design and Method Selection:
A versatile kinetics-controlled coating method was employed to deposit colloidal TiO2 spheres along the surface of the SiO2 spheres for the formation of SiO2@TiO2 (amorphous). The obtained precursor was then subjected to preannealing in a furnace and followed by rapid quenching the samples in liquid nitrogen (-196 °C) to obtain the defect-rich SiO2@TiO2 spheres.
2：Sample Selection and Data Sources:
Colloidal SiO2 spheres were prepared according to St?ber’s method. The shell of amorphous TiO2 layer was uniformly deposited along the surface of the SiO2 spheres without using any surfactants via a versatile kinetics-controlled coating method.
3：List of Experimental Equipment and Materials:
Tetraethyl orthosilicate (TEOS), butyl titanate (TBOT), ethanol, concentrated ammonia solution (26 wt%), and NaOH were used.
4：Experimental Procedures and Operational Workflow:
The resultant products were separated and collected, followed by washing with deionized water and ethanol for 3 times, respectively. Then, the obtained powders were dried at 100 °C overnight.
5：Data Analysis Methods:
The structural analysis of the as-prepared samples was carried out by transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), Field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, UV-vis diffuse reflectance spectra (DRS), Photoluminescence (PL) spectra, and Electron paramagnetic resonance (EPR) spectra.
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Tetraethyl orthosilicate
TEOS
Aladdin Co., Ltd. China
Used in the synthesis of SiO2 spheres
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Butyl titanate
TBOT
Aladdin Co., Ltd. China
Used in the synthesis of SiO2@TiO2 core-shell nanostructures
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Ethanol
Tianjin Zhiyuan Chemical Reagents Co., Ltd
Used as a solvent in the synthesis process
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Concentrated ammonia solution
26 wt%
Tianjin Zhiyuan Chemical Reagents Co., Ltd
Used in the synthesis of SiO2 spheres and SiO2@TiO2 core-shell nanostructures
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NaOH
Tianjin Zhiyuan Chemical Reagents Co., Ltd
Used in the synthesis of TiO2 hollow spheres
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Transmission electron microscopy
Tecnai F30
Holland
Used for structural analysis of the as-prepared samples
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Field-emission scanning electron microscope
Hitachi SU8010
Used for examining the morphology of the samples
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X-ray diffractometer
Bruker D8
Used for monitoring the crystal structure of the samples
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X-ray photoelectron spectroscopy
Thermo Fisher Scientific XPS ESCALAB 250Xi
Used for XPS measurements
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Raman spectrometer
Bluker Senterra
Used for measuring Raman spectra
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UV-vis spectrophotometer
Hitachi
Used for measuring UV-vis diffuse reflectance spectra (DRS)
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Fluorescence spectrophotometer
Hitachi F-4500
Used for recording Photoluminescence (PL) spectra
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Electron paramagnetic resonance spectrometer
Bruker Elexsys E580
Used for obtaining Electron paramagnetic resonance (EPR) spectra
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