M-Doped TiO2 and TiO2-M xO y Mixed Oxides (M = V, Bi, W) by Reactive Mineralization of Cellulose - Evaluation of Their Photocatalytic Activity.

M-doped TiO₂ and mixed oxides M _xO _y-TiO₂ (M = V, Bi, W) were synthesized by the reactive mineralization of ash-free filter paper under anhydrous conditions. Mixtures of metal chlorides (TiCl₄ with VOCl₃, WCl₆, or BiCl₃) were reacted directly with cellulose, and three different Ti/M atomic ratios were used (99, 19, and 9). The resulting materials consist of original nanoflower assemblies of needle-shaped primary particles. Their physicochemical characteristics were investigated by various techniques (X-ray diffraction, diffuse-reflectance UV/Vis spectroscopy, electron microscopy, and elemental analysis). The incorporation of the doping metal or the formation of mixture of oxides with TiO₂ (WO₃, Bi₂O₃) depends on the metal and the proportions used. The photocatalytic activities of the materials were tested for the degradation of phenol. The vanadium-doped materials exhibit true solid-solution formation and their band gaps shift into the visible range. [ABSTRACT FROM AUTHOR]