Facile one-pot synthesis of Eu, N-codoped mesoporous titania microspheres with yolk-shell structure and high visible-light induced photocatalytic performance
A new type of Eu, N-codoped mesoporous TiO2 microspheres with yolk–shell structure (TiO2@void@TiO2) was successfully synthesized by a facile one-pot hydrothermal method at low temperature (180 °C). The physical and chemical properties of as-synthesized samples, such as morphology, crystal phase, surface elements composition, porous structure, specific surface area and optical response, were characterized in detail. The resultant samples were porous microspheres with a diameter of about 1–3 μm, and were composed of a large number of smaller nanoparticles. An interior circular cavity in each microsphere was formed between core and shell to construct a special yolk–shell structure, and a large number of pores were produced in shell and yolk by CO2 gas bubbles resulting from hydrothermal decomposition of the urea molecules, which tremendously increased the specific surface area and the pore volume of as-obtained samples. The absorption edges of Eu, N-codoped TiO2 were extended to longer wavelength, which led to notable absorption in the visible-light region. The photocatalytic performances of all samples were evaluated by photocatalytic decoloration of rhodamine B and methyl orange under visible light irradiation (λ > 420 nm). Eu, N-codoped TiO2 with 0.1 at.% Eu dopant showed the highest photocatalytic activity, the efficiency of which was 5 times higher than that of Degussa P25. The enhanced photocatalytic performance could be attributed to the synergic effects of many factors, such as high specific surface area, large pore volume and strong absorption to visible light, which were created by the Eu, N-codoping and the unique yolk–shell structure. Based on the above results, the mechanism of enhanced photocatalysis on Eu, N-codoped TiO2 under visible light was proposed.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (214 K)Download as PowerPoint slideHighlights► Eu, N-codoped TiO2 with yolk-shell structure was synthesized by one-pot method. ► Synergic effects of two dopants to improve photocatalytic activity were discovered. ► Yolk–shell structure allowed multiple reflections of light within interior cavities. ► The resultant material presented high visible-light induced photocatalytic activity.
Journal: Applied Catalysis A: General - Volumes 435–436, 5 September 2012, Pages 86–92