| Recently,a lot of research topics focus on the study of nano-Ti02 photocatalyst and its application in environmental protection.However,there are still some drawbacks,such as difficulty in recycling and low adsorption to solar light,which limit its industrial applications.In order to improve the photocatalytic performance of catalyst,our research aim to design and prepare some novel photocatalytic materials.Firstly,a robust Ti02 film,which was coated on Si02 substrate,was fabricated;on the other hand,we also synthesized a novel 3D peony-like Ti02 microstructure exposed with a large percentage of{001} facets to degradating high concentration organic pollutants.The SEM,HRTEM,AFM,XRD,XPS,BET,Raman spectra,FT-IR,EDS,and PL techniques were used to characterize and analysis the basic physicochemical properties of the as-prepared catalysts.Meanwhile,the photocatalytic activity of catalysts was evaluated by degradating methyl orange and methylene blue under UV light irradiation.The main research findings are as follows.(1)A very stable TiO2 hydrosol was first been prepared via a simple sol-gel process using titanium butoxide and polyethylene glycol(PEG)as precursor and porogen respectively in the presence of acetylacetone and acetic acid,respectively.The Ti02 hydrosol was coated on SiO2 substrate,which was treated with Piranha solution to activate surface silanol group(Si-OH),using dip-coating method.Highly homogenous and transparent film was fabricated by either a hydrothermal method or by calcination process.The results show that the film with a thickness of 320 nm was anatase phase,having porous structure,and mainly made up of Ti02 nanoparticles with size of 8-12 nm.And the film surface was smooth with surfaces roughness of Ra=1.01 nm and Rq= 1.26 nm.More importantly,we also have a further study about the relationship between the molecular weight or adding amount of PEG in Ti02 hydrosol and the porous structure of film.The photocatalytic degradation of MO in aqueous solution was carried out in order to evaluate the photocatalytic activity of the TiO2 film.The results show that the photocatalytic performance of TiO2 film prepared by annealing was better than those prepared by hydrothermal process.When the PEG with molecular weight of 1000 and adding amount of 5.0 g,the as prepared TiO2 film showed the highest photocatalytic performance.We also found that the photocatalytic of TiO2 film was increased linearly with increasing coating times of TiO2 hydrosol.The-degradation ratio of MO under UV light irradiation reached 98%and did not change significantly after the catalysts used several times.(2)In consideration of the high photocatalytic activity,efficiency adsorption of light irradiation and convenient for recycling,a novel 3D peony-like TiO2 microstructure material with a large percentage of {001} facets exposed was fabricated via a facile solvothermal method by using titanium chloride as precursor,ethanol as solvent,and hydrogen fluoride as capping agent,respectively.We systematically study the influences of those parameters,such as the concentration of HF and TiCl4,the reaction temperature and time,and even the solvents,on the morphology evolution and crystal structure.The results show that the TiO2 nanosheet gradually grow bigger and bigger with increasing the concentration of HF,and the percentage of exposed {001} facets was increased from 34%to 98%as well;once the concentration of HF was up to a certain value,those nanosheets self-assemble and form to peony-like hierarchically microstructures.With raising reaction temperature or prolonging reaction time,the products were transformed from microspheres composed of short hexagonal prisms to microflowers composed of ultrathin nanosheets;at the same time,the phase structure was also changed from unknown compound TiO1.6F1.9 to anatase TiO2.Furthermore,solvent also played a crucial role in the forming process of peony-like Ti02.The photocatalytic experiment was tested by degradating of MB under UV light irradiation.The results show that the as-prepared 3D peony-like Ti02(97%)performed better than commercial P25(68%),keeping the cumulative mass loss rate below 15%,and still maintain a degradation rate of-95%after 5 recycles.In order to further improve the photocatalytic activity and extend the recombination time of photoinduced electron-hole pairs,a composite catalyst Ag@Ti02 was synthesized by a simple photo-deposition method.The results show that the Ag nanoparticles with size of?6.14 nm were homogenously loaded on TiO2 nanosheets,and the composite catalyst outperform pure catalyst in the photodegradation of MB under a very weak UV light irradiation(power:8 W,light intensity:0.4 mW cm-1). |
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