Fluorescence Spectra and Quantum Yield of TiO2 Nanocrystals Synthesized by Alcohothermal Method
SONG Cui-hong1,LI Yan-ting2,LI Jing1,WEI Yong-ju1,HU Yu-zhu2,WEI Yu1*
1. College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang 050016, China 2. Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
Abstract:Fluorescence spectra and fluorescence quantum yield of TiO2 nanocrystals were studied. Using tetra n-butyl titanate as a starting material, a facile alcohothermal technique was used to synthesize TiO2 nanocrystals. As can be seen from the transmittance electron microscopy (TEM) image, TiO2 nanocrystals with a relatively uniform particle size distribution of <10 nm are present in the transparent sol. The transparent sol presents a strong stable fluorescence emission with a maximum at 450 nm, which is greatly dependent on the size quantization effects,defect energy level and the surface state of TiO2 nanocrystals. The quantum yield (γ) of TiO2 was determined by the relative comparison procedure, using freshly prepared analytical purity quinine sulfate in 0.05 mol·L-1 H2SO4 as a relative quantum yield standard. The emission quantum yield of TiO2 nanocrystals prepared in alcoholic media was calculated to be about 0.20 at wavelengths ranging from 330 to 370 nm, which was much higher than the values reported in previous works. So, it is supposed that nano-TiO2 will be applied as a potential quantum dots fluorescence probe in biological analysis.
Key words:TiO2 nanocrystals;Alcohothermal technique;Quinine;Fluorescence quantum yield;Quantum size effect;Surface state
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