Abstract
Visible-light driven ordered mesoporous metal ion doped anatase TiO2 photocatalysts were synthesized via a hard-template chemical route. The effects of metal ion doping on the band energy level, surface area, pore volume, pore diameter, and photocatalytic properties of the ordered mesoporous anatase TiO2 were systematically investigated. X-Ray photoelectron spectra and UV-vis absorption spectra indicate that the W and Mn ions enter into the lattice of anatase TiO2 in the presence of W6+ and Mn3+/Mn4+, resulting in a band gap transition with a red shift from the ultraviolet to the visible range, preventing the recombination rate of electron-hole pairs, therefore the photocatalytic activity can be greatly enhanced in the visible region. There exists an optimal doping level of 5 mol% W and 0.5 mol% Mn, respectively, with 95% MB and 82% MB being photocatalytically decomposed within 70 min under the visible light for 5% W and 0.5% Mn doped mesoporous anatase TiO2, respectively. Importantly, W ion doped TiO2 displays much higher photocatalytic efficiency than Mn ion doped TiO2, which can be attributed to the presence of much higher Lewis surface acidity of W6+ doped TiO2 surface with a higher affinity for chemical species having unpaired electrons than Mn doped TiO2. In addition, the W doping induced grain refinement, highly crystalline state, large surface area and large pore size additionally contribute to the improved photocatalytic activity of the mesoporous W-doped TiO2 samples. The enhanced ability to absorb visible light makes the ordered mesoporous metallic ion doped TiO2 an effective photocatalyst for solar-driven applications.
Published Version
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