Controllable Synthesis Of Titanium Functional Materials From Peroxotitanium Complex (PTC) And The Application

Titanium dioxide nanoparticles have attracted great attention in the semiconductor photocatalysis field due to its wide band gap and good stability. It has wide application for wastewater purfication, air cleaning, anti-bacteria and self-cleaning. Moreover, controllable synthesis of nanoparticles with particular structure and composition is a great research point, as the properties of nano materials can be affected by the particle sizes, morphologies and phases. However, due to the high reactivity of the titanium precursor, it is very difficult for controllable synthesis TiO₂ nanopartilces at ambient conditions. In our work, we utilized a stable water-base peroxo-titanum complex (PTC) as a precursor to controllably synthesize titanium fuctional materials at low temperature, and investigated the structures, properties as well as application as follows.1. We described a systemic approach for preparation of different phases and morphologies titanium dioxide nanoparticles with peroxotitanium complex (PTC) as a precursor by adjusting the system pH value at amident conditions. The pH value and molar ratio have obvious influence on the final phases. Low pH (pH 0) and high H2O₂/Ti molar ratio (> 20:1) are benefit for rutile phase. There is an optimum H2O₂/Ti molar ratio for brookite formation at pH about 1. When the pH value reach to 3 or above, anatase particles are obtained whatever the [H2O₂]/[Ti] ratio is. Photocatalytic properties of different products were measured by decomposing methylene blue. The spherical anatase phase showed higher photocatalytic degradation rates for methylene blue than others. Futhermore, we described a one-step and solution (water-based) synthesis method for preparing rutile nanorods form PTC precursor at 100 oC. In this reaction process, rutile stucture is directly decided by the PTC precursor, without any transition phase. The size of the nanorods could be controlled by simply changing the concentration of the precursor. It is found that the smaller rutile nanoparticles show higher photocatalytic activity.2. SiO₂/TiO₂ composite sol was prepared from the PTC precursor. It showed not only high photocatalytic activity but also hydrophibility. The composite sol can be used for different architectural substrates by adding especially surfactant and assistant agent for about three months at outdoor experiment. Furthermore, the sol showed good activity formaldehyde-decomposing activity when used on texile. We discussed the photocatlytic activity on different substrates. It was proved that the cotton material shown the best activity due to its large amount of surface hydroxyl. The decomposing ctivity can reach 70% and the formaldehyde concentration was less than 2 ppm in 22 hours.3. The anatase TiO₂ sol prepared from Peroxotitanium Complex (PTC) at low temperature was used as the additive for photo-anode of flexible dye sensitized solar cells (DSSC). It is found that the photoelectric performance of DSSC was obviously increased by 50% with the addition of TiO₂ sol. Furthermore, we investigated the effects of the sol content and reaction time on the photoelectric performance. It is proved that there is an optimal addition value for the DSSC application. When the content (volume) of PTC sol is 10% and refluxing time reaches to 9 hours, the best photoelectric performance is obtained.