Preparation Of Porous TiO₂Film By Microbe Template Method And Its Photocatalytic Activity

Nano-porous TiO₂film gets more and more attention because it has manyadvantages in solar cells and wastewater treatment, and how to prepare a highactivity porous film is becoming a hot spot of research.In this paper, the hierarchical TiO₂films were prepared by the microbe templatemethod and assisted by the sol-gel process. The photocatalytic activities were evaluated bythe degradation of MB solition or MO solutin under visible light or ultraviolet ligh as wellas the hydroxyl radical measurement. The internal structures and surface morphologiesof materials were characterized by FE-SEM, TEM, XRD, contact angel measurement, andUV-vis spectroscopy et al. Then we futher studied the photocatalytic activity underdifferent parameters, such as the calcination time、the proportion of titanium sol and themicrobial templates、the amount of gold or silver and the thickness of the films and so on.The result indicates that the thin film of hierarchical micro-mesoporous structured TiO₂and the TiO₂/Au（Ag）/TiO₂were all successfully fabricated via. the microorganismtemplated method. This method can improve the efficiency of sunlight utilization. Underthe same experimental conditions, the photocatalytic activity of the porous TiO₂filmssynthesized by the microorganism templated method is superior to the P25or ordinaryTiO₂films in degradation of methyl blue or methyl orange. And the hydroxyl radicalmeasurement result demonstrates that the capability of hydroxyl radical formation at theinterface between TiO₂and water is in positive correlation with the photocatalytic activity.It was also found that the calcination time, the ratio of the Ti precursor and themicroorganism template, and the film thickness have no significant impact o n thephotocatalytic activities. We also explored the flagellum as a template to prepare TiO₂/Au（Ag）/TiO₂composite film sandwich structure. This structure was found to play a role instabilizing metal nanoparticles. The photocatalytic activities of TiO₂/Au（Ag）/TiO₂towarddegradation of methyl orange increase with the increase of the loading amounts of Au orAg under visible light，but no significant effect under ultraviolet light. The research shows that through microbial templates to prepare the hierarchicalporous TiO₂thin films and TiO₂/Au（Ag）/TiO₂films; owing to the special multiple classeshole structure, it can make the light on the multiple scattering, thereby improving theutilization ratio of sunlight. This method provided a feasible way in the utilization rate oflight.