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Anatase TiO nanocrystal colloids with high dispersion and photocatalytic activity were rapidly synthesized from peroxo-titanium-acid precursor by microwave-assisted hydrothermal method within 30 min at low temperature (120-180 °C). The transmission electron microscopy results indicate that the as-prepared TiO have a narrow particle size distribution (25-29 nm) and high dispersion. The crystal structure of all these products are pure anatase phase (XRD, Raman), and they show good crystallinity and large surface area (N adsorption-desorption measurements BET). The results of the UV-Visible absorbance and Fourier transform infrared spectra indicate that the surface peroxo group Ti(O) still remains in TiO nanoparticles prepared by microwave-assisted hydrothermal method at 120 °C, and this surface peroxo group can be decomposed effectively by drying at 140 °C. The photocatalytic activity of the as-prepared TiO were evaluated by the degradation of reactive brilliant red X-3B, it is found that the as-prepared TiO exhibited good photocatalytic performance. Moreover, the existence of surface peroxo group greatly suppressed the photocatalytic activity of the TiO nanoparticles. [ABSTRACT FROM AUTHOR]

Highlights: [•] W6+-doped TiO2 nanocrystal colloids were prepared by hydrothermal methods. [•] The properties of TiO2 nanocrystal colloids can be tuned by tungsten doping. [•] W6+-doped TiO2 nanocrystal colloids show higher stability and dispersity. [•] W6+-doped TiO2 nanocrystal colloids show higher photocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: The Sn4+ doped anatase TiO2 nanocrystals with various amounts of dopant Sn4+ ions were prepared from peroxo-metal-complex precursor by solvothermal method and characterized by XRD, TEM, HRTEM, XPS, ICP-AES and UV–vis spectrophotometer. The experimental results indicated that the dopant Sn4+ substituted Ti4+ in the lattice of TiO2, which reflected in the lattice expansion in both a- and c-direction and change of the binding energy. All the Sn4+ doped TiO2 nanocrystal samples appeared to be anatase evenly with dopant level up to 10mol%. The effect of dopant Sn4+ ions and reaction solvents on physicochemical properties of the obtained Sn4+ doped anatase TiO2 nanocrystals had been discussed. In addition, the growth mechanism and microstructure evolution of Sn4+ doped anatase TiO2 nanocrystals had been suggested. The photocatalytic activity of the Sn4+ doped anatase TiO2 nanocrystals was tested by the degradation of phenol. Compared with the undoped TiO2 sample, the enhanced photocatalytic activity of the Sn4+ doped anatase TiO2 nanocrystals could be attributed to modification of the optical properties and surface state by doping the optimum concentration of Sn4+ ions. [Copyright &y& Elsevier]

Abstract: The preparation of Ti1−x Sn x O2 nanocrystal colloids from peroxo-metal precursor by hydrothermal method was reported in this work. The obtained materials were investigated by means of XRD, Raman, TEM, XPS, ICP-AES, N2 adsorption–desorption measurements (BET), PL and UV–vis spectroscopies technology. Photocatalytic degradation of phenol was studied under UV illumination. The results indicated that Ti1−x Sn x O2 nanocrystal colloids were obtained in the nanometer scale (less than 10nm) and the crystallite size was smaller than pure TiO2. Anatase phase, mixture phase (anatase and rutile) and rutile phase of Sn-doped TiO2 samples were formed, when x <0.04, 0.04< x <0.06 and x ≥0.06, respectively. The Sn4+ dopants presented substitution Ti4+ into the lattice of TiO2 alongside increasing the surface oxygen vacancies and the surface hydroxyl groups. Regarding photocatalytic activity, Sn-doped TiO2 samples (TiSn3) were nearly four times higher than undoped samples. This obvious beneficial effect could be attributed to high surface area, optimal crystalline phase and surface state modifications. [ABSTRACT FROM AUTHOR]