Preparation and photocatalytic activity of nanoglued Sn-doped TiO2

In this paper, Sn-doped TiO(2) photocatalyst was prepared and immobilized on a glass substrate using an about-to-gel SiO(2) sol as a nanoglue. The characterization of the Sn-doped TiO(2) by XRD showed that 5% Sn content is formed by anatase and rutile crystallites. Characterization of the nanoglued photocatalyst by the BET measurement, TEM, and SEM showed that the photocatalyst was a nanoporous material with a high-surface area. The Sn-doped TiO(2) was uniformly dispersed within the three-dimensional network of the silica in the form of nanoparticles. The nanoglued photocatalyst showed high photocatalytic activity during the degradation of penicillin under UV light. The effect of different Sn content on the amount of hydroxyl radical was discussed by using salicylic acid as probe molecules. The results show that an appropriate amount of Sn dopant can greatly increase the amount of hydroxyl radicals generated by TiO(2) nanoparticles, which are responsible for the obvious increase of photocatalytic activity.     

SiO2/TiO2复合气凝胶的孔道结构研究

为了在常压干燥下制备高比表面积且具有多级孔道结构的SiO2/TiO2复合气凝胶,以正硅酸乙酯、钛酸丁酯为原料,利用低聚体聚合将分相平行引入到溶胶凝胶过程中,获得SiO2/TiO2醇凝胶,并通过溶剂替换技术实现气凝胶的常压干燥制备.不同硅钛比气凝胶的内部结构研究表明:合成的气凝胶是由纳米SiO2和TiO2颗粒分散复合而成的介孔块体,其中Ti—O—Ti、Si—O—Si和Ti—O—Si键相互交织.气凝胶的结构变化是分相与溶胶凝胶过程相互竞争的结果.Si含量能显著改善气凝胶的结构,当n(Ti)∶n(Si)为3∶1时,比表面积高达712.2 m2/g,平均孔径为3.36 nm;当n(Ti)∶n(Si)为1.5∶1时,复合气凝胶具有明显双连续孔道,比表面积高,同时孔状结构清晰.     

医用NiTi合金表面溶胶-凝胶法制备TiO2-SiO2薄膜

采用溶胶－凝胶法在ＮｉＴｉ形状记忆合金表面制备了ＴｉＯ_２－ＳｉＯ_２复合薄膜,在提高医用ＮｉＴｉ合金的抗腐蚀性方面,收到了显著的效果．运用电化学方法对不同组成的ＴｉＯ_２－ＳｉＯ_２薄膜在模拟体液中的腐蚀行为进行了研究,结果表明,随薄膜中 Ｔｉ／Ｓｉ比的增加,ＴｉＯ_２－ＳｉＯ_２薄膜的抗腐蚀性增强．划痕试验表明 ＴｉＯ_２－ＳｉＯ_２（Ｔｉ／Ｓｉ＝４：１）膜与ＮｉＴｉ合金基体具有较高的界面结合强度．用原子力显微镜（ＡＦＭ）对ＴｉＯ_２－ＳｉＯ_２薄膜的表面形貌及表面粗糙度进行观察和分析,解释并讨论了ＴｉＯ_２－ＳｉＯ_２薄膜的配方组成与其抗腐蚀性的关系,ＳｉＯ_２含量较少时,薄膜结构致密,膜层均匀平滑,且膜基结合力好,作为医用ＮｉＴｉ合金的表面保护层,可以使其耐腐蚀性有显著提高．     

减反射可见光与反射近红外线双功能镀膜玻璃

采用溶胶-凝胶工艺,用提拉法在光伏玻璃上制备了玻璃/TiO2-SiO2/SnO2∶F/SiO2减反射可见光与反射近红外双功能膜。用拟合方法研究了TiO2掺量对TiO2-SiO2膜层折射率的影响、以及溶胶中水含量对SiO2膜层折射率的影响;研究了快速热处理温度对SnO2∶F膜结构和方块电阻的影响,用紫外-可见光谱(UV-Vis)测试了膜层的透射率,用扫描电镜(SEM)观察了膜层的表面形貌。结果表明,TiO2掺量可以使TiO2-SiO2膜层的折射率在1.49~1.97之间变化,SiO2溶胶中的水含量能够在膜面上形成微孔,降低SiO2膜层的折射率。通过优化工艺,制备出了在可见光范围平均透过率约为96%、1120nm波长近红外起始反射的双功能复合膜。对得到的结果进行了讨论。     

Nanocomposite of Cu-TiO2-SiO2 with high photoactive performance for degradation of rhodamine B dye in aqueous wastewater

The nanocomposite of Cu-TiO2-SiO2 photocatalyst have been prepared by a sol-gel method, which is used for the degradation of Rhodamine B (RB) as a probe that is notorious organic compound present in dyes wastewater. Morphological and structural characteristics of the Cu-TiO2-SiO2 nanocomposite were studied with low temperature N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (DRS). The Fourier transformed infrared spectroscopy (FT-IR) analysis shows the enhanced chemical bonding of O-Ti and O-Ti-O after the composition of Cu and SiO2 species into TiO2. It is found that the Cu-TiO2-SiO2 nanocomposite exhibits much higher photocatalytic activity under both UV light and visible light irradiation as compared with that over commercial titania (Degussa P25) toward the dyes wastewater containing RB. The photodegradation rate of RB (5 mg/L) can reach above 95.0% under sunlight after 3 h. The addition of SiO2 not only inhibites the crystal growth and anatase-to-rutile transformation of TiO2 nanocatalyst, but also enhances the adsorption of organic compounds. Cu-doping extends the light response to the visible region. Synergetic effects between Cu-SiO2 and TiO2 have been investigated, which provides a good way and material in the degradation field of dyes wastewater.     

TiO2对CaO-Al2O3-SiO2系玻璃晶化机理的影响

使用差热分析（DTA）方法研究了TiO2对CaO－Al2O3－SiO2系玻璃晶化机理的影响，发现在CaO－Al2O3－SiO2系玻璃中，引入TiO2有助于玻璃网络聚合程度的降低，从而导致玻璃的粘度减小，转变温度Tg和析晶峰温度Tp的降低.玻璃的析晶难易程度和析晶峰温度的高低不存在相互对应关系．CaO－Al2O3－SiO2系玻璃中，不管是否加入TiO2，均以表面晶化为主，TiO2的晶核剂效果不显著．充分的核化热处理也不能促使含TiO2的CaO－Al2O3－SiO2系玻璃发生体积晶化，TiO2的含量越高，核化热处理后玻璃的表面晶化效果越显著．     

热处理温度对TiO2/SiO2复合气凝胶光催化性能的影响

采用溶胶–凝胶法在常压下经不同温度热处理制备了TiO2/SiO2复合气凝胶光催化剂,利用XRD、TGA和BET等手段对其微观结构进行表征,以甲基橙溶液光催化降解实验评价其光催化性能,研究了热处理温度对TiO2/SiO2复合气凝胶的微观结构及光催化性能影响规律.结果表明:随着热处理温度升高,TiO2/SiO2复合气凝胶中锐钛矿结晶度升高,晶粒尺寸增大,比表面积减小,使TiO2/SiO2复合气凝胶对甲基橙溶液的光催化降解活性呈现先升后降的变化趋势.当热处理温度为700℃左右,紫外光照20 min TiO2/SiO2复合气凝胶对甲基橙溶液的降解率达到95.4%.     

超临界流体干燥法制备TiO2/ Fe2O3 和TiO2/ Fe2O3/ SiO2 复合纳米粒子及光催化性能

以TiCl₄ 、Fe (NO₃ )₃·9H₂O 和Na₂SiO₃19H₂O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO₂/ Fe₂O₃ 和TiO₂/ Fe₂O₃/ SiO₂ 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO₂/ Fe₂O₃ 复合粒子与单组分TiO₂ 比较, 复合粒子光催化活性高于单组分的TiO₂, 6h 苯酚降解率高达95.9 %。SiO₂ 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO₂ 纳米粒子的热稳定性。复合光催化剂中Fe₂O₃ 最佳掺入量为0.06 %, SiO₂ 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO₂ 以锐钛矿型形式存在, SiO₂ 以无定性形式存在。比较了不同制备方法制得的TiO₂/ Fe₂O₃ 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。     

HNO3处理对TiO2纳米薄膜的光催化活性和表面微结构的影响

通过sol-gel工艺分别在钠钙玻璃和预涂SiO2涂层的钠钙玻璃基体上制备了TiO2光催化纳米薄膜．然后用1mol／L HNO3水溶液对煅烧后的薄膜进行酸处理。用X射线光电子能谱(XPS)、扫描电镜(SEM)和紫外可见光谱(UV—VIS)对酸处理前后TiO2纳米薄膜进行了表征。用甲基橙水溶液的光催化脱色来评价TiO2薄膜的光催化活性。结果表明：SiO2涂层能有效阻止钠离子从玻璃基体向TiO2薄膜的扩散，普通玻璃表面的TiO2纳米薄膜经HNO3处理后，薄膜的光催化活性明显增强。这是由于TiO2纳米薄膜中的钠离子浓度降低以及表面羟基含量增加的缘故。     

铁铕共掺杂的TiO_2空心微球的制备及光催化活性

通过溶胶-凝胶法制备铁铕共掺杂的TiO_2(Fe~(3+)-Eu~(3+)/TiO_2)空心微球,采用XRD、TEM、BET和XPS等对样品进行表征,以亚甲基蓝(MB)的光催化降解为目标反应,评价其光催化活性。结果表明:SiO_2微球表面均匀地包覆了1层TiO_2,超声有利于提高SiO_2@TiO_2复合微球间的分散性,同时也发现煅烧前对SiO_2@TiO_2复合微球进行研磨处理后所得的Fe~(3+)-Eu~(3+)/TiO_2空心微球部分塌陷,而未研磨和煅烧后研磨所得Fe~(3+)-Eu~(3+)/TiO_2空心微球完整性较好。XRD和BET分析表明,Fe~(3+)-Eu~(3+)/TiO_2空心微球为锐钛矿且具有良好的介孔结构,铁铕共掺杂在TiO_2空心微球中产生协同作用,使Fe3+-Eu3+/TiO2空心微球的粒径进一步减小,比表面积增大。当Fe~(3+)的掺杂量为1.0%、Eu~(3+)的掺杂量为0.5%时,Fe~(3+)-Eu~(3+)/TiO_2空心微球的光催化活性最高。     

Mixed films of TiO(2)-SiO(2) deposited by double electron-beam coevaporation

We used double electron-beam coevaporation to fabricate TiO(2)-SiO(2) mixed films. The deposition process included oxygen partial pressure, substrate temperature, and deposition rate, all of which were real-time computer controlled. The optical properties of the mixed films varied from pure SiO(2) to pure TiO(2) as the composition of the films varied accordingly. X-ray diffraction showed that the mixed films all have amorphous structure with a SiO(2) content of as low as 11%. Atomic force microscopy showed that the mixed film has a smoother surface than pure TiO(2) film because of its amorphous structure.

Linear and Bruggeman's effective medium approximation models fit the experimental data better than other models.

     

Preparation and photocatalytic properties of nanometer-sized magnetic TiO2/SiO2/CoFe2O4 composites

Magnetic TiO2/SiO2/CoFe2O4 nanoparticles (TiO2/SCFs) were prepared by a sol-gel process in a reverse microemulsion combined with solvent-thermal technique. TiO2/SCFs were characterized by Fourier transform infrared spectrometry, thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Raman spectrometry, TEM, BET specific surface area measurement, and magnetic analysis. Structure analyses indicated that TiO2/SCFs presented a core-shell structure with TiO2 uniformly coating on SiO2/CoFe2O4 nanomagnets (SCFs) and typical ferromagnetic hysteresis. TiO2/SCFs showed larger specific surface area and better photocatalytic activities than TiO2 and TiO2/CoFe2O4 photocatalysts prepared by the same method. The doping interaction between TiO2 and CoFe2O4 reduced thanks to the inert SiO2 mesosphere.     

TiO2 coating of high surface area silica gel by chemical vapor deposition of TiCl4 in a fluidized-bed reactor

TiO2 was deposited on high surface area porous silica gel (400 m2g(-1)) in a fluidized bed reactor. Chemical vapor deposition was employed for the coating under vacuum conditions with TiCl4 as precursor. Nitrogen physisorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy were applied to characterize the obtained TiO2-SiO2 composites with different Ti loadings up to 5 wt%. Only a slight decrease in the specific surface area was detected at low Ti loadings. At a Ti loading of 2 wt%, TiO2 was found to be highly dispersed on the SiO2 surface likely in form of a thin film. At higher Ti loadings, two weak reflections corresponding to anatase TiO2 were observed in the diffraction patterns indicating the presence of crystalline bulk TiO2. High resolution XPS clearly distinguished two types of Ti species, i.e., Ti-O-Si at the interface and Ti-O-Ti in bulk TiO2. The presence of polymeric TiOx species at low Ti loadings was confirmed by a blue shift in the UV-vis spectra as compared to bulk TiO2. All these results point to a strong interaction between the TiO2 deposit and the porous SiO2 substrate especially at low Ti loadings.     

Development of titanium-dioxide-based aerogel catalyst with tunable nanoporosity and photocatalytic activity

Nanostructured highly porous TiO(2)/WO(3)/Fe(3+) aerogel composite photocatalysts are prepared, characterized and tested for model photocatalytic reactions. The catalyst structure is tailored to capture environmental pollutants and enable their decomposition in situ under both ultraviolet (UV) and visible light through oxidation to smaller benign molecules. A novel and green method is utilized to prepare the unique surfactant-templated aerogel composite photocatalyst that has a highly accessible porous nanostructure with high surface area and tailored pore size distribution. The sol-gel process is combined with supercritical extraction and drying. Supercritical drying with heat treatment results in titanium dioxide with anatase crystal form. Templates used further enable retention and tuning of the nanopore structure and surface properties. The synthesized catalysts were characterized using SEM, FIB, XRD and porosimetry prior to post-evaluation in model reactions. The bandgap of the catalyst particles was also determined using diffuse reflectance. The resulting aerogel TiO(2)/WO(3)/Fe(3+) has similar photocatalytic capability compared to highly optimized commercial Degussa P25 under UV exposure and offers much superior photocatalytic capability under visible light exposure. The model reaction utilized employed methylene blue (MB) photooxidation under visible and UV light.     

TiO2@SiO2微球的制备及其光催化性能研究

采用模板法以钛酸丁酯为钛源,SiO2为模板球,制备出了TiO2包覆SiO2微球。利用SEM、TEM、XRD、EDS对样品形貌、结构和成分进行了表征分析,并测试了样品的光催化性能。结果表明TiO2@SiO2微球的光催化性能优于用相同方法制得的TiO2的光催化性能,当使用TiO2@SiO2微球为光催化剂时,在光照180min后甲基橙的降解率达到82%,而相同方法制得的TiO2为56%,较后者提高了26%,具有良好的光催化活性。     

Low-temperature Preparation of Photocatalytic TiO2 Thin Films on Polymer Substrates by Direct Deposition from Anatase Sol

Anatase TiO2 sol was synthesized under mild conditions （75℃ and ambient pressure） by hydrolysis of titaniumn-butoxide in abundant acidic aqueous solution and subsequent reflux to enhance crystallization. At room temperature and in ambient atmosphere, crystalline TiO2 thin films were deposited on polymethylmethacrylate （PMMA）, SiO2-coated PMMA and SiO2-coated silicone rubber substrates from the as-prepared TiO2 sol by a dip-coating process. SiO2 layers prior to TiO2 thin films on polymer substrates could not only protect the substrates from the photocatalytic decomposition of the TiO2 thin films but also enhance the adhesion of the TiO2 thin films to the substrates. Field-emission type scanning electron microscope （FE-SEM） investigations revealed that the average particle sizes of the nanoparticles composing the TiO2 thin films were about 35-47 nm. The TiO2 thin films exhibited high photocatalytic activities in the degradation of reactive brilliant red dye X-3B in aqueous solution under aerated conditions. The preparation process of photocatalytic TiO2 thin films on the polymer substrates was quite simple and a low temperature route.     

常压干燥法制备TiO2气凝胶

以钛酸丁酯为原料, 乙酸为有机配体, 甲酰胺为干燥控制化学添加剂(DCCA), 采用溶胶-凝胶法和溶剂置换等后续工艺, 实现了块状TiO₂气凝胶催化剂的常压干燥法制备, 并考察了有机配体对气凝胶结构性能的影响。采用XRD、BET、SEM、EDS及DSC-TG对样品进行表征。结果表明: 当有机配体与钛酸丁酯物质的量之比为0.9时, 制备的样品性能最佳, 该TiO₂气凝胶样品为非晶态, 表观密度为0.25 g·cm^-3, 比表面积716.5 m²·g^-1, 平均孔径19.1 nm; 在850℃大气气氛下热处理2 h后, 比表面积为122.4 m²·g^-1, 平均孔径23.4 nm, 具有较高光催化活性; 经1000℃热处理后, TiO₂晶型仍为锐钛矿相, 热稳定性较好, 光催化活性有所降低。未采用有机配体制备的TiO₂气凝胶表观密度为0.57 g·cm^-3, 比表面积为482.2 m²·g^-1。有机配体的使用更有利于制备出表观密度较小、比表面积较高的TiO₂气凝胶。     

Granularity in ion-beam-sputtered TiO(2) films

TiO(2)-SiO(2) multilayer dielectric stacks that were deposited by ion-beam sputtering were found to have a granular structure. The grains were in the TiO(2) layers rather than in the SiO(2) layers. Their formation was due to the heating of the film during deposition. When the apparatus was modified to reduce the substrate temperature, the granularity was eliminated.     

磁性纳米TiO2/SiO2/Fe3O4光催化剂的制备及表征

以纳米Fe3O4磁粉为核心，采用溶胶一凝胶法制备了TiO2／SiO2／Fe3O4复合光催化剂．用XRD、TEM及元素分析对其结构和表面形貌进行了表征．以具有偶氮染料结构的甲基橙水溶液为目标反应物，评价其光催化活性．结果表明，所制TiO2／SiO2／FeaO4样品为双层包覆型结构，SiO2为中间层，最外层是锐钛矿型的TiO2,该复合光催化剂对甲基橙溶液有较高的光催化活性，并具有可利用其磁性回收重用的特点，应用前景广泛。     

Characterization of Sol-gel-derived TiO2 and TiO2-SiO2 Films for Biomedical Applications

In order to improve the corrosion resistance and biocompatibility of NiTi surgical alloy, TiO2 and TiO2-SiO2 thin films were prepared by sol-gel method. The surface characteristics of the film, which include surface composition, microstructure and surface morphology, were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS), respectively. A scratching test was used to assess the interface adhesive strength between the film and substrate. The corrosion resistance of NiTi alloy coated with oxide films were studied by anodic polarization curves measurement in biological solution. Additionally, a preliminary study of the in vitro bioactivity of the films was conducted. The results indicated that TiO2 and TiO2-SiO2 (Ti/Si=4:1) films have higher electrochemical corrosion resistance and can be used as protective layers on NiTi alloy. In addition, TiO2-SiO2 composite films have better bioactivity than TiO2 film.