SiO2柱层状钛酸的制备及光催化性能

采用分步反应法制备SiO2柱层状钛酸(SiO₂-H₂Ti₄O₉)光催化材料, 研究了制备过程中烷基胺的链长、胺预撑后的洗涤方式以及与正硅酸乙酯(TEOS)水热反应时间等因素对SiO₂-H₂Ti₄O₉结构的影响. 以亚甲基蓝(Methylene Bule, MB)为探针反应物, 考察了SiO₂柱层状钛酸的光催化性能. 结果表明, 随着烷基胺链长增加, 层间距增大, 有利于在层间引入TEOS; 用1:1的乙醇水溶液洗涤正十二胺撑后的产物的结晶度显著高于用无水乙醇洗涤的产物; 胺撑后的产物与TEOS在130℃条件下水热反应两次可得到层间距为1.45nm、比表面积为148.4m²/g、结构较规整的SiO₂-H₂Ti₄O₉柱层状材料. 该柱层状材料对亚甲基蓝具有较高的光催化活性.     

Effects of Fe-doping on the photocatalytic activity of mesoporous TiO2 powders prepared by an ultrasonic method

Highly photoactive nanocrystalline mesoporous Fe-doped TiO(2) powders were prepared by the ultrasonic-induced hydrolysis reaction of tetrabutyl titanate (Ti(OC(4)H(9))(4)) in a ferric nitrate aqueous solution (pH 5) without using any templates or surfactants. The as-prepared samples were characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), N(2) adsorption-desorption measurements, UV-visible adsorbance spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by the photocatalytic oxidation of acetone in air. The results showed that all the Fe-doped TiO(2) samples prepared by ultrasonic methods were mesoporous nanocrystalline. A small amount of Fe(3+) ions in TiO(2) powders could obviously enhance their photocatalytic activity. The photocatalytic activity of Fe-doped TiO(2) powders prepared by this method and calcined at 400 degrees C exceeded that of Degussa P25 (P25) by a factor of more than two times at an optimal atomic ratio of Fe to Ti of 0.25. The high activities of the Fe-doped TiO(2) powders could be attributed to the results of the synergetic effects of Fe-doping, large BET specific surface area and small crystallite size.     

SiO2/TiO2柱撑层状钛酸的制备及表征

采用预膨润技术成功制备了SiO2/TiO2柱撑层状钛酸。将氢型钛酸TiO2(H)于正丙胺溶液中利用离子交换方法得到正丙胺插层的钛酸C-3TiO,C-3TiO在正硅酸乙酯和异丙醇钛的混合溶剂中160℃溶剂热处理2天,得到SiO2/TiO2柱撑层状钛酸。利用X-射线衍射,红外光谱,透射电子显微镜,热重-差热分析等手段对材料进行表征,结果表明制备材料具有层状结构,层间距为1.1nm。     

Preparation and characterization of visible-light-driven TiO2 photocatalyst Co-doped with nitrogen and erbium

A series of nitrogen and erbium co-doped TiO2 photocatalyst was prepared by sol-hydrothermal method. The structure and properties of the photocatalyst were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (DRS). The XRD and BET results showed that co-doping inhibited the increase of crystallite size and enlarged specific surface areas. XPS spectroscopy indicated nitrogen atoms were incorporated into TiO2 lattice, and erbium atoms mostly existed in the forms of Er2O3. A shift of the absorption edge to the lower energy and four absorption bands located at 654, 544, 524 and 489 nm attributed to the 4f transitions of 4I15/2 --> 4F2/9, 4I15/2 --> 4S3/2, 4I15/2 --> 2H11/2, 4I15/2 --> 4F7/2 of Er3+ were observed using DRS spectroscopy. The catalytic efficency was evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the photocatalytic performance of the co-doped TiO2 was related with the hydrothermal temperature and the molar ratio of N/Ti, and they showed higher acitivites than pure TiO2. Results determined by fluorescence technique revealed that irradiation (lambda > 400 nm) of TiO2 photocatalyst dispersed in MO solution induces the generation of the highly active hydroxyl radicals (OH). It indicated the photocatalytic activities of TiO2 photocatalyst were correlation with the formation rate of hydroxyl radicals (OH) and other active oxygen species.     

Photocatalytic degradation of gaseous benzene over TiO2/Sr2CeO4: preparation and photocatalytic behavior of TiO2/Sr2CeO4

The paper demonstrates that the photocatalytic activity of TiO(2) towards the decomposition of gaseous benzene in a batch reactor can be greatly improved by loading TiO(2) on the surface of Sr(2)CeO(4). The research investigates the optimum loading amount of TiO(2) on Sr(2)CeO(4) in enhancing the photocatalytic activity of TiO(2). The prepared photocatalyst was characterized by XRD, UV-vis diffuse reflectance and XPS analyses. TiO(2) is loaded on Sr(2)CeO(4) at 773K. TiO(2)/Sr(2)CeO(4) absorbs much more visible light than TiO(2). The XPS spectrum shows that there are Ti, O, C, Sr elements on the surface of the TiO(2)/Sr(2)CeO(4), and that the binding energy value of Ti2p transfers to a lower value. TiO(2)/Sr(2)CeO(4) demonstrates 2.0 times the photocatalytic activity of pure TiO(2). Based upon these observations, the mechanistic role of Sr(2)CeO(4) in the photocatalytic oxidation reaction has been suggested.     

层状K2Ti4O9的制备及其酸交换及剥离反应

以高温固相反应法、硬脂酸法及硬脂酸钾法三种不同的方法制备了超细层状钛酸钾盐K2Ti4O9。利用X射线衍射及扫描电镜对钛酸盐的结构及形貌进行了确定,考察了不同反应历程对产物尺寸及结构的影响,比较了不同方法的优缺点,并对层状钛酸钾盐的酸交换及剥离反应进行了探讨。     

Fabrication characterization and activity of a solar light driven photocatalyst: cerium doped TiO2 magnetic nanofibers

A novel magnetic separable composite photocatalytic nanofiber consisting of TiO2 as the major phase, CeO(2-y) and CoFe2O4 as the dopant phase was prepared by sol-gel method and electrospinning technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum (UV-vis DRS) and vibrating sample magnetometer (VSM). The photocatalytic activity of the resultant CoFe2O4-TiO2 and CeO(2-y)/CoFe2O4-TiO2 nanofibers was evaluated by photodegradation of methylene blue (MB) in an aqueous solution under xenon lamp (the irradiation spectrum energy distribution is similar to sunlight) irradiation in a photochemical reactor. The results showed that the dopant of Ce could affect the absorbance ability and photo-response range. The sample containing 1.0 wt% CeO(2-y) exhibited the highest degradation with 35% for MB under simulate solar light irradiation. Furthermore, the as-synthesized composite photocatalytic nanofibers could be separated easily by an external magnetic field, thus it might hold potential for application in wastewater treatment.     

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.     

Photocatalytic activity of TiO2 doped with boron and vanadium

Boron (B)- and vanadium (V)-doped TiO(2) photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N(2) physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO(2) was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO(2) increased as the boron doping increased, with high conversion efficiency for 9mol% B doping.     

Photoinduced hydroxyl radical and photocatalytic activity of samarium-doped TiO(2) nanocrystalline

Sm(3+)-doped TiO(2) nanocrystalline has been prepared by sol-gel auto-combustion technique and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and also UV-vis diffuse reflectance spectroscopy (DRS). These Sm(3+)-doped TiO(2) samples were tested for methylene blue (MB) decomposition and *OH radical formation. The analysis of *OH radical formation on the sample surface under UV irradiation was performed by fluorescence technique with using terephthalic acid, which readily reacted with *OH radical to produce highly fluorescent product, 2-hydroxyterephthalic acid. It was observed that the presence of Sm(3+) ion as a dopant significantly enhanced the photocatalytic activity for MB degradation under UV light irradiation because both the larger specific surface area and the greater the formation rate of *OH radical were simultaneously obtained for Sm(3+)-doped TiO(2) nanocrystalline. The adsorption experimental demonstrated that Sm(3+)-TiO(2) had a higher MB adsorption capacity than undoped TiO(2) and the adsorption capacity of MB increased with the increase of samarium ion content. The results also indicated that the greater the formation rate of *OH radical was, the higher photocatalytic activity was achieved. In this study, the optimum amount of Sm(3+) doping was 0.5 mol%, at which the recombination of photo-induced electrons and holes could be effectively inhibited, the highest formation rate of *OH radicals was, and thereby the highest photocatalytic activity was achieved.     

Synthesis and characterization of visible light driven mesoporous nano-photocatalyst MoO3/TiO2

A novel mesoporous-structured photocatalyst MoO3/TiO2 was synthesized through a modified sol-gel method by using P123 as the template, and the resulting nano-photocatalysts were characterized by X-ray diffraction (XRD), N2 adsorption measurements, transmission electron microscope (TEM), UV-vis spectroscopy, XPS and Raman techniques. Low-angle XRD and TEM images show the lack of long-range order in the as-prepared MoO3/TiO2, but the Mo species are homogenously dispersed on the anatase matrix. According to the results of N2 ads-desorption, the calcined products possess the high surface area and the pore size distribution centered between 4-7 nm. The calcined meso-MoO3/TiO2 materials exhibit the high photocatalytic activity for the degradation of MB (methylene blue) under visible light radiation.     

Preparation and application of nanoglued binary titania-silica aerogel

Nanoglued binary titania (TiO2)-silica (SiO2) aerogel, as a novel type of photocatalyst, has been synthesized on glass substrates. Using an about-to-gel SiO2 sol as nanoglue, anatase TiO2 aerogel was immobilized into a three-dimensional mesoporous network of the SiO2. Factorial designs were employed to optimize both TiO2 aerogel and binary TiO2-SiO2 aerogel synthesis. Characterization of the as-prepared TiO2 and binary samples by surface area, porosity, and surface chemical composition showed that the photocatalysts were high-surface-area nanoporous materials, with a Ti4+ valency. The binary aerogel exhibited high photocatalytic activity for the degradation of methylene blue (MB) under simulated solar light; the reaction followed the pseudo first-order Langmuir-Hinshelwood (L-H) kinetic model. Fluorescence spectroscopy revealed that the hydroxyl (*OH) radical was formed during the illumination of the binary TiO2-SiO2 aerogel in a solution of probe molecules, which corroborates the probable mechanism of hydroxyl radical oxidation of contaminants in photocatalytic reactions.     

溶胶-凝胶法制备TiO_2-Al_2O_3复合光催化剂及其表征

以钛酸四正丁酯为钛源,异丙醇铝为铝源,采用溶胶-凝胶法制备了TiO2-Al2O3复合光催化剂,考察其对甲基橙的吸附性能和在紫外光照射下的光催化活性。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、傅里叶变换红外光谱(FT-IR)、N2吸附-脱附等对催化剂的晶相结构、化学组成及BET比表面积和孔径分布等进行了表征。结果表明TiO2-Al2O3复合光催化剂由TiO2和Al2O3组成,其中TiO2为单一的锐钛矿晶相,Al2O3为非晶态,Al2O3的存在可抑制TiO2晶粒的生长。在n(Ti)/n(Al)=12,500℃煅烧3h制得的TiO2-Al2O3复合光催化剂比表面积达99.21m2/g,平均孔径为22.39nm,累计孔容积为0.4493cm3/g。在500℃煅烧制得的复合光催化剂具有最佳的光催化活性和吸附性能。与纯TiO2相比,相同条件下TiO2-Al2O3复合光催化剂的光催化活性和吸附性能都有较大提高。     

Nitrogen-doped TiO2 nanotubes with enhanced photocatalytic activity synthesized by a facile wet chemistry method

Nitrogen-doped TiO₂ nanotubes with enhanced photocatalytic activity were synthesized using titanate nanotubes as raw material by a facile wet chemistry method. The resulting nanotubes were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and UV-vis absorption spectroscopy, etc. The photocatalytic activity of nitrogen-doped TiO₂ nanotubes was evaluated by the decomposition of methylene blue under artificial solar light. And it was found that nitrogen-doped TiO₂ nanotubes exhibited much higher photocatalytic activity than undoped titanate nanotubes.     

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/活性炭复合体超临界沉淀法制备及其光催化性能

以活性炭为载体、超临界二氧化碳为流体、钛酸丁酯为前驱体,用超临界流体沉积法制备TiO2/活性炭（TiO2/AC）复合体。用X射线衍射（XRD）、扫描电镜（SEM）、比表面积分析（BET）、热重-差热（TG-DTA）对TiO2/AC进行表征。以紫外灯为光源,偶氮类染料亚甲基蓝为标准降解物,考察TiO2/AC复合体的光催化...     

Fabrication and characteristics of three-dimensional flower-like titanate nanostructures

A novel and facile approach has been developed to fabricate three-dimension (3D) flower-like titanate nanostructures from Ti powders. The synthesized flower-like titanate nanostructures were composed of many thin nanoribbons and have an ultrahigh specific surface area of 572.3 m2/g. After high temperature heat treatment, the flower-like titanate nanostructures were totally transformed into corresponding anatase TiO2 nanostructures without destroying their 3D hierarchical structural motif. The flower-like TiO2 nanostructures exhibited high photocatalytic activity for photodecomposition of methyl blue, and they could possibly be further used in photovoltaic cell, sensors, Li-ion batteries, and so on.     

镍掺杂锆柱撑钛酸盐的制备、表征与光催化性能

采用高温固相加水热合成方法制备出钛酸盐单分子层。掺镍的聚合羟基锆离子溶液与钛酸盐单分子层悬浮液共混,通过剥离重堆积技术制得镍掺杂锆柱撑钛酸盐材料(NZPT)。用X射线衍射(XRD)、N2吸附分析、扫描/透射电镜(SEM/HR-TEM)和紫外可见吸收光谱(UV-vis)对材料晶体结构、化学组成、微观形貌和孔结构等性质进行表征。以紫外-可见光催化降解酸性红G作为探针反应考察镍的掺入对Zr柱撑钛酸盐复合材料(ZPT)光催化活性的影响。结果表明:掺镍柱撑材料的催化活性均高于未掺镍ZPT,其中,NZPT-0.10呈现出最佳的催化活性,这与材料掺杂后形成的更大比表面积以及主客体间的电子耦合有关。     

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.     

柠檬酸钠辅助水热法制备钛酸钙及其紫外光催化性能

以钛酸四正丁酯((C4H9O)4Ti)水解沉淀的钛羟基氧化物和硝酸钙(Ca(NO3)2.4H2O)为反应物料,加入适宜浓度的矿化剂氢氧化钾和络合剂柠檬酸钠,在温度200℃水热反应12h后得到了CaTiO3粉体。利用SEM、XRD、TEM等对CaTiO3的形貌、尺寸和结构进行表征,通过光催化降解罗丹明B(RhB)对其紫外光催化性能进行了研究。结果表明柠檬酸钠在CaTiO3水热合成过程中起到关键性作用,其形貌和紫外光催化性能随着柠檬酸钠浓度改变而发生巨大变化。