Study Of The Different Coating Orders Influence Of N-F-TiO₂Films On Their Preparation And Photocatalytic Activities

In previous studies, TiO₂was the most commonly used catalyst because of itsnon-toxicity, reasonable cost, high availability, photochemical stability andrelatively high photocatalytic activity. Its application scope is very extensive, such assewage treatment, air purification, solar energy utilization, antibacteria, preventingmist and clean function etc. Photocatalysis is a promising method that has greatpotential for conversion of photon energy into chemical energy and decompositionof pollutants in air and water including dyes, surfactants, pesticides and all kinds ofdifficult biodegradation of toxic organic pollutants. Degradation products are CO₂and H₂O and inorganic ions.TiO₂with a band gap of3.2eV can be photoexcited under irradiation of UVlight （λ<387.5nm）. TiO₂particles with UV light produces holes and electrons. Mosthydroxyl radicals are generated upon the oxidation of OH or H₂O by thesephotogenerated holes. Such holes are principally responsible for the destruction oforganic species. But UV light is only about2-4%of sunlight. Therefore,considerable effort has been made to increase the absorption of TiO₂in the visiblelight region to improve its visible light response through various surfacemodifications such as various doped metal or nonmetal oxides.This study evaluates the photodegradation efficiency of acid red B andmethylene blue in a visible light and TiO₂film system. TiO₂film catalyst wasprepared by the sol–gel method. N-F-TiO₂films were prepared by three differentcoating orders, denoted as N-F-TiO₂（1）, N-F-TiO₂（2）, N-F-TiO₂（3）, respectively.Their photocatalytic activities were compared through selects of experiments. Theeffect of irradiation time, light power and solution acidity on degradation of acid redB was investigated by UV-vis specra. The result showed that N-F-TiO₂（3） has thehightest photocatalytic activity for degradation of10mg/L acid red B. Whenirradiation time is18h, degradation rate is up to100%.N-F-Ce-TiO₂films were prepared by three different coating orders, denoted as N-F-Ce-TiO₂（1）,N-F-Ce-TiO₂（2）, N-F-Ce-TiO₂（3）, respectively. Their photocatalyticactivities were compared through selects of experiments. T2he effect of irradiationtime, light power and solution acidity on degradation of methylene blue wasinvestigated by UV-vis specra. The result showed that N-F-Ce-TiO₂（3） has thehightest photocatalytic activity for degradation of10mg/L methylene blue. Whenirradiation time is12h, degradation rate is up to100%.N-F-Fe-TiO₂films were prepared by three different coating orders, denoted asN-F-Fe-TiO₂（1）, N-F-Fe-TiO₂（2）, N-F-Fe-TiO₂（3）, respectively. Their photocatalyticactivities were compared through selects of experiments. The effect of irradiationtime, light power and solution acidity on degradation of methylene blue wasinvestigated by UV-vis specra. The result showed that N-F-Fe-TiO₂（3） has thehightest photocatalytic activity for degradation of10mg/L methylene blue. Whenirradiation time is12h, degradation rate is up to100%.