Fe^(3+)-Doped Anatase TiO_2 Study Prepared by New Sol-Gel Precursors

FeTi_1-O_2（= 0.00,0.05,0.10） nanocomposites are synthesized using a sol-gel method involving an ethanol solvent in the presence of ethylene glycol as the stabilizer,and acetic acid as the chemical reagent.Their structural and optical analyses are studied to reveal their physicochemical properties.Using the x-ray diffractometer（XRD）analysis,the size of the nanoparticles（NPs） is found to be 18-32 nm,where the size of the NPs decreases down to 18 nm when Fe impurity of up to 10% is added,whereas their structure remains unchanged.The results also indicate that the structure of the NPs is tetragonal in the anatase phase.The Fourier transform infrared spectroscopy analysis suggests the presence of a vibration bond（Ti-O） in the sample.The photoluminescence analysis indicates that the diffusion of Fe^（3＋） ions into the TiO_2 matrix results in a decreasing electron-hole recombination,and increases the photocatalytic properties,where the best efficiency appears at an impurity of10%.The UV-diffuse reflection spectroscopy analysis indicates that with the elevation of iron impurity,the band gap value decreases from 3.47 eV for the pure sample to 2.95 eV for the 10 mol% Fe-doped TiO_2 NPs.

A Fundamental DFT Study of Anatase(TiO2) Doped with 3d Transition Metals for High Photocatalytic Activities

Anatase（TiO_2） has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made for anatase to increase its capability in utilizing more abundant visible light. We investigated the doped anatase with the most promising 3d transition metal elements, and the results showed that the visible light absorption intensity was increased significantly due to the reduced band gap and the cavitation effects. As compared to other 3d transition metals, Cu was found to be the most effective one in improving anatase photocatalytic effects. In addition, greater Cu concentration doped in the anatase increased the photocatalysis effects but reduced the anatase stability, therefore, an optimized Cu concentration should be considered to optimize the anatase photocatalysis activity.

Characterization and Electrochemical Properties of Nanostructured Zr-Doped Anatase TiO_2 Tubes Synthesized by Sol–Gel Template Route

A series of nanostructured Zr-doped anatase TiO_2 tubes with the Zr/Ti molar ratio of 0.01, 0.02, 0.03, and0.09 were prepared by a sol–gel technology on a carbon fiber template. The electrochemical performance of Zr-doped anatase TiO_2 as anodes for rechargeable lithium batteries was investigated and compared with undoped titania. Tests represented that after 35-fold charge/discharge cycling at C/10 the reversible capacity of Zr-doped titania（Zr/Ti = 0.03） reaches 135 m A h g^（-1）, while the capacity of undoped titania（Zr/Ti = 0） yielded only 50 m A h g^（-1）. Based on the results of the physicochemical investigation, three reasons of improving electrochemical performance of Zr-doped titania were suggested. According to the scanning electron microscopy and transmission electron microscopy, Zr^（4＋） doping induces a decrease in nanoparticle size, which facilitates the Li＋diffusion. The Raman investigations show the more open structure of Zr-doped TiO_2 as compared to undoped titania due to changing of the unit cell parameters, that significantly affects on the reversibility of the insertion/extraction process. The electrochemical impedance spectroscopy results indicate that substitution of Zr^（4＋） for Ti^（4＋） into anatase TiO_2 has favorable effects on the conductivity.

Preparation and Performance of Si^4＋ -doping Rod-shaped TiO2 Powder by Nonhydrolytic Sol-gel Method

Titania（TiO2） nanorod powder was prepared by nonhydrolytic sol-gel method using titanic chloride（TiCl4） as titanium source, methylene dichloride（CH2Cl2） as solvent, absolute ethyl alcohol（CH（-3）CH2OH） as oxygen donor. The effects of Si^（4＋） doping on the TiO2 nanocrystalline phase transformation temperature were systematically researched. The results showed that when the molar ratio of Ti^（4＋） to Si^（4＋） is 1 to1.3, TiO2 prepared by calcination at 1 100 ℃ for 1 hour exhibits rod shape and has good photocatalytic activity. Doping of Si^（4＋） makes glass phase core-shell structure forming on the surface of anatase crystal particles, which can inhibit crystal phase transformation and raise the transformation temperature, making TiO2 stable in anatase phase at 1 200 ℃.