Synthesis Of TiO₂ – Based Porous Materials And Investigation Of Its Photocatalytic Performance

TiO2 has attracted enormous attention because of its excellent catalytic activity, chemical stability, super-hydrophilic, sterilization and disinfection, low-cost and non-toxicity. However, the wide band gap of TiO2 limited the absorbance of solar light. In addition, there are still some other drawbacks of TiO2 which restrict their applications in the field of photocatalysis, such as low quantum yield and easy recombination of photo-generated e-/h+ pairs. Therefore, the TiO2-based porous materials were synthesized to improve their photocatalytic activity,which were characterized by X-ray diffracatometry, Brunauer-Emmertt-Teller, UV-vis diffuser reflectance, Scanning electron microscopy, Energy dispersive spectrum, Thermogravimetric and Photocurrent measurement. The datiled works were as follows:The first, Nd-doped TiO2 and Sn/Nd-codoped TiO2 porous materials were synthesized, whose photocatalytic properties was studied.(1) With polystyrene spheres as template, tetrabutyl titanate and Nd(NO3)3·6H2O as the titanium and Nd source, Nd-doped TiO2 porous materials were successfully synthesized using a sol-gel method and calcination at high temperaure. The influence of dopant amount and calcination temperature on the photocatalytic performance was investigeted. The results demonstrated that the dopant with Nd could enhance the photocatalytic activity. Because Nd doping not only increase the surface area of TiO2 by hindering the growth of the nanoparticles, but also suppress the recombination of e-/h+ pairs. The sample of 0.5% Nd-TiO2-550 oC showed the best photocatalytic activity. After UV irradiation 15 min, the degradation rate of methyl orange reached up to 99.5%.(2) Using the similar method as described above, the Sn/Nd-codoped TiO2 porous materials were synthesized. And the influence of dopant amount and calcination temperature on the photocatalytic performance was studied. The results demonstrated that the band gap of the as-synthesized samples was relatively narrower compared to the pure anatase phase of TiO2. And both Nd and Sn were in favor of the separation of e-/h+ pairs. The sample of 0.5% Nd-TiO2-550 oC showed the optimal photocatalytic activity. After UV irradiation 15 min, the degradation rate of methyl orange got to 99.5%.The second, Ag-doped TiO2, Ag/ rutile phase TiO2-codoped anatase phase TiO2 porous materials were synthesized, whose photocatalytic property was conducted.(1) With polystyrene spheres as template, porous TiO2 monoliths were prepared by sol-gel method. And then Ag was deposited on the surface of the porous TiO2 via UV-visible irridation for AgNO3 solution. And the effect of Ag was investigated on the photocatalytic performance. The sample of 3% Ag-TiO2 showed the best photocatalytic activity. After irradiation 60 min, the degradation rate of rhodamine B reached to 98.04%.(2) The porous 3% Ag-TiO2 monoliths were prepared by the same method described above. With TiCl4 as the titanium source, the as-prepared porous 3% Ag-TiO2 monoliths as precursor, Ag/rutile phase TiO2-codoped anatase phase TiO2 porous materials were obtained utilized low-temperature chemical bath deposition method. And the impact of rutile phase TiO2 on the photocatalytic performance was studied. The samples showed an excellent photocatalytic performance when the dopant amount reach to 5%. After irradiation 60 min, the degradation rate of rhodamine B reached to 100%.The third, CdS-doped TiO2 and Ag/CdS-codoped TiO2 porous materials were prepared, whose photocatalytic properties was performed.(1) Uniform-distribution CdS in porous TiO2 monoliths were successfully synthesized using sol-gel method in the presence of polystyrene spheres as template, followed by calcination at high tempreture and hydrothermal method. In order to evaluate the photocatalytic activity of the as-prepared samples, the photodegradation for rhodamine B was performed under simulated sunlight irridation. Experimental results showed that 3% CdS-doped porous materials exhibited the high photocatalytic performance with photodegradation efficiency of 99.49% after simulated sunlight irradiation for 60 min.(2) A certain amount of Ag was deposited on the surface of the CdS-doped TiO2 porous materials. The samples exhibited good photocatalytic performance when the dopant amount of CdS was 3%. After irradiation 60 min, the degradation rate of rhodamine B achieved up to 99.99%.At last, SrTiO3-doped TiO2 porous materials were synthesized and their photocatalytic properties were studied.Under alkaline conditions, SrTiO3-doped TiO2 porous materials were synthesized using porous TiO2 monoliths and Sr(NO3)2 as source by hydrothermal reaction. The influence of SrTiO3 content on the photocatalytic properties was carried out. Among of the samples, 20% SrTiO3-doped TiO2 porous materials showed the best photocatalytic performance. After irradiation 60 min, the degradation rate of rhodamine B got to 99.19%.