A novel dopant-free TiO2 photocatalyst (Vo.-TiO2), which is self-modified by a large number of paramagnetic (single-electron-trapped) oxygen vacancies, was prepared by calcining a mixture of a porous amorphous TiO2 precursor, imidazole, and hydrochloric acid at elevated temperature (450 °C) in air. Control experiments demonstrate that the porous TiO2 precursor, imidazole, and hydrochloric acid are all necessary for the formation of Vo.-TiO2. Although the synthesis of Vo.-TiO2 originates from such a multicomponent system, this synthetic approach is facile, controllable, and reproducible. X-ray diffraction, XPS, and EPR spectroscopy reveal that the Vo.-TiO2 material with a high crystallinity embodies a mass of paramagnetic oxygen vacancies, and is free of other dopant species such as nitrogen and carbon. UV/Vis diffuse-reflectance spectroscopy and photoelectrochemical measurement demonstrate that Vo.-TiO2 is a stable visible-light-responsive material with photogenerated charge separation efficiency higher than N-TiO2 and P25 under visible-light irradiation. The Vo.-TiO2 material exhibits not only satisfactory thermal- and photostability, but also superior photocatalytic activity for H2 evolution (115 μmol h−1 g−1) from water with methanol as sacrificial reagent under visible light (λ>400 nm) irradiation. Furthermore, the effects of reaction temperature, ratio of starting materials (imidazole:TiO2 precursor) and calcination time on the photocatalytic activity and the microstructure of Vo.-TiO2 were elucidated.
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.