A New Strategy To Improve The Photocatalytic Performance Of Nano - TiO 2 And Its Mechanism

As a kind of semiconductor photocatalysis, the physical and chemical properties of nano-Ti O2 differ from the other numerous semiconductor, has become a hotspot in scientific field. However, Ti O2 have been restricted for two points as photocatalyst. On the one hand, the recombination of photocharges is high, leads to a low photocharge sepration efficiency. It is necessary to improve the quantum efficiency of Ti O2 by modification. On the other hand, Ti O2 can only adsorb the UV light because the wide bandgap. One of the most effective tactics is to tune the bandgap in order to use the solar energy. Based on this, nanosized Ti O2 with cantaining different contents of rutile phase were synthesized, and focus on the influence of surface chloride to the resulting rutile Ti O2. Further subject to hydrogenation treatment to expand the visible region absorption, then modified by H3PO4 to promote the ability of oxygen adsorption. It would favorable for improving the sepration of photocharges and photoactivity. In addition, the mechanism is also revealed, more details is as follows:Firstly, nanosized Ti O2 containing different cantents of turile phase were controllably synthesized by a hydrochloric acid-modified hydrothermal process and explored which factor determines the photoactivity of the Ti O2, and reveal the mechanism. The results show that, rutile Ti O2 which has appropriate amount chloride on surface shows high activity for photoelectrochemistry. The mechanisms of photocatalytic activity increased is: The residual chloride could effectively capture photogenerated holes, so as to promote the photogenerated charges separation of rutile Ti O2. As a result, the mechanism of this enhancement is promotes the production of ·OH.And then, Ti O2 rutile nanorods were reduced by hydrogen, the visible region activity of the catalyst were investigated particularly. The results show that the photoresponse of Ti O2 is expanded into the visible region and the color is changed from white to dark blue. Appropriate time hydrogenation treatment would promote the photogerated charge separation, attributed to the introduction of Ti3+ defect / oxygen vacancies. This doped Ti O2 have a new proper-level surface states below the conduction band bottom, so as to broaden the response of the visible light. Then, the Ti O2 was modified by phosphoric acid to increase the amount of O2 adsorption on-OH, in order to promote the photogenerated charges separation of the hydrogen reduced Ti O2 and enhance the photoactivity.This work would provide a new method for the design and synthesis of high-performance photocatalyst for degrading environmental pollutant.