Preparation of Cr‐doped TiO2/SiO2 Photocatalysts and their Photocatalytic Properties

Cr‐doped TiO₂/SiO₂ nanostructured materials were prepared employing a layer‐by‐layer assemblym technique. TiO₂ colloids were synthesized by a sol‐gel method using TiCl₄ as a precursor. The experimental results showed that sphere‐type TiO₂ particles on SiO₂ exhibited uniform shape and a narrow size distribution. The amount of Ti (wt %) increased as a function of the number of the coating layers. The coatingv layers was composed of anatase titania nanocrystals at 550 °C. The onset of band‐gap transition for Crdoped TiO₂/SiO₂ showed a red shift compared with that for the undoped TiO₂/SiO₂. And the photocatalytic activity of Cr‐doped TiO₂/SiO₂ was higher than that of undoped sample.     

Preparation and Photocatalytic Activity of Ce,H3PW12O40 co-doped TiO2 Hollow Fibers

A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.     

Photocatalytic Activity of Fe and Ce Co‐doped Mesoporous TiO2 Catalyst under UV and Visible Light

The catalysts of un‐doped, single‐doped and co‐doped mesoporous titanium dioxide (MTiO₂) were prepared by a template method with tetrabutyltitanate (Ti(OC₄H₉)₄) as a Ti source material and Pluronic P123 as a template. The photo‐absorbance of the obtained catalysts was measured by UV‐vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange (MO) (50 mg/L) in an aqueous solution. It was shown that the co‐doped MTiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The effect of Fe and Ce co‐dopants on the material properties was investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption‐desorption isotherm measurement. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m²/g. The photocatalytic activity of MTiO₂ co‐doped with Fe and Ce was markedly improved due to the synergistic actions of the two dopants.     

Preparation and Photocatalytic Activity of Mesoporous TiO2 Photocatalyst Co‐doped with Fe and H3PW12O40

The mesoporous titanium dioxide (MTiO₂) photocatalysts co‐doped with Fe and H₃PW₁₂O₄₀ were synthesized by template method using tetrabutyl titanate (Ti(OC₄H₉)₄), Fe(NO₃)k₃9H₂Oand H₃PW₁₂O₄₀ as precursors and Pluronic P123 as template. The as‐prepared photocatalyst was characterized by N₂ adsorption‐desorption measurements, X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐vis adsorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl blue (MB) (50 mg/L) in an aqueous solution. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m²/g. The results of MB photodecomposition showed that co‐doped mesoporous TiO₂ exhibited higher photocatalytic activities than un‐doped, single‐doped mesoporous TiO₂ under UV and visible light irradiation. It was shown that the co‐doped MTiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The synergistic effect of Fe and H₃PW₁₂O₄₀ co‐doping played an important role in improving the photocatalytic activity.     

Two‐Dimensional Hollow TiO2 Nanoplates with Enhanced Photocatalytic Activity

Two‐dimensional anatase TiO₂ hollow nanoplates were firstly synthesized through a facile synthesis route by using α‐Fe₂O₃ nanoplates as removable templates. Two‐dimensional hollow TiO₂ nanoplates with different ratios of anatase and rutile phases were obtained by adjusting the calcining temperature. The average diameters were around 600 nm, and the shell thickness was approximately 30 nm. The photocatalytic performance of TiO₂ was investigated by decomposing rhodamine B under simulated sunlight. Among the TiO₂ samples, the anatase TiO₂ hollow nanoplates manifested a significant enhancement in the photocatalytic performances. The excellent catalytic performance can be attributed to the unique structure of the two‐dimensional anatase TiO₂ hollow nanoplates, including a large surface area and increased dye–photocatalyst contact areas as well as more active sites for photodegradation.     

WO3/TiO2 复合纤维的制备及储能光催化性能

以钛酸正丁酯为前驱体, 采用静电纺丝技术制得了纯锐钛矿TiO2纤维, 并以其为基质, 通过水热法制备了具有异质结构的WO3/TiO2复合纤维. 利用X射线衍射仪(XRD)、 扫描电子显微镜(SEM)、 能量色散光谱仪(EDS)、 透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等对样品的结构和形貌进行了表征. 以罗丹明B的脱色降解为模型反应, 考察了样品的光催化性能和储能光催化性能. 结果表明, 花状WO3微球包裹在TiO2纤维上, 得到了具有异质结构的WO3/TiO2复合纤维光催化剂. WO3与TiO2复合有利于光生载流子的输运和分离, 增强了体系的量子效率, 提高了光催化活性. WO3/TiO2 复合纤维经光照处理后, 在黑暗条件下显示出储能光催化特性.     

Template‐free Fabrication of Hierarchical Macro‐/mesoporous N‐doped TiO2/graphene Oxide Composites with Enhanced Visible‐light Photocatalytic Activity

Hierarchical macro‐/mesoporous N‐doped TiO₂/graphene oxide (N‐TiO₂/GO) composites were prepared without using templates by the simple dropwise addition mixed solution of tetrabutyl titanate and ethanol containg graphene oxide (GO) to the ammonia solution, and then calcined at 350 °C. The as‐prepared samples were characterized by scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller (BET) surface area, X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐Vis absorption spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under visible‐light irradiation. The results show that N‐TiO₂/GO composites exhibited enhanced photocatalytic activity. GO content exhibited an obvious influence on photocatalytic performance, and the optimal GO addition content was 1 wt%. The enhanced photocatalytic activity could be attributed to the synergetic effects of three factors including the improved visible light absorption, the hierarchical macro‐mesoporous structure, and the efficient charge separation by GO.     

Si掺杂TiO2纤维的溶胶-凝胶法制备及其光催化活性

采用溶胶-凝胶法并结合水蒸气活化制备了Si掺杂TiO₂纤维, 通过TG-DSC, XRD, FT-IR, UV-Vis-DRS, N₂吸附-脱附, SEM等手段对纤维样品的结构参数及其表面形貌进行了表征, 并以活性艳红X-3B模拟废水体系评价了其光催化活性．结果表明, 与纯TiO₂产物相比, 适量Si掺杂制得的产物是具有丰富介孔结构的TiO₂长纤维, 不仅热稳定性和晶型稳定性俱佳, 而且光催化活性得以显著提高, 经900 ℃热处理后仍能保持结晶完好的锐钛矿相; 在Si/Ti摩尔比为0.15时, 其比表面积和孔容最大, 光催化活性最佳, 该纤维作为光催化剂反应75 min, 水中X-3B的降解率可达99.6%.     

ZnO/ZnSe复合纳米结构的制备及可见光光催化性能

通过热水解法, 以氧化锌为模板, 成功制备出形貌均一的ZnO/ZnSe复合纳米结构. 为了对比不同O/Se比对光催化性能的影响, 保持其它反应参数不变, 调节还原剂水合肼的用量, 得到不同硒化程度的ZnO/ZnSe复合纳米结构. 采用场发射扫描电子显微镜、 X射线衍射仪和透射电子显微镜对样品的形貌及结构进行了表征, 通过测试该复合结构对亚甲基蓝的可见光催化降解评估了其光催化效率. 结果表明, 与纯ZnO比, ZnO/ZnSe复合结构在可见光区域和紫外光区域的光吸收范围变宽, 显示出较高的光催化效率. 原因在于ZnSe导带上的电子在扩散势能的作用下迁移到ZnO的导带上, 而空穴仍保留在ZnSe价带, 这样有助于光生电子和空穴对的分离, 降低其复合机率, 从而提高ZnO的光催化效率.     

纳米TiO2/碳化树脂复合催化剂的合成及其光催化性能研究

利用一种简单、快速的方法合成了纳米TiO₂/碳化树脂(B)复合催化剂,对其组成、结构、尺寸及其光催化性能进行了表征.结果表明,该复合材料为由碳、氢、氧和钛等4种元素组成的纳米材料,尺寸约30nm,其中Ti和O的堆积结构为锐钛矿型;在该复合材料中,B为具有活性基团和不同长度碳-碳共轭链的大分子,且与TiO₂之间存在着某种化学作用,复合材料所具有的特殊电子结构不仅使其能吸收紫外-可见区的全程光波,而且对光生电荷具有很高的分离能力,从而表现出较高的光催化活性.     

掺硼纳米TiO2的制备及光催化性能研究

采用改进的Sol-gel方法,制备了单分散椭球形微孔结构的掺B纳米TiO₂光催化剂,并用TG-DTA、XRD、XPS、UV-Vis、TEM、BET等手段进行表征.以难生化降解的染料罗丹明B为目标降解物,采用HPLC检测,通过不同光照时间下染料降解率考察了产物的光催化活性.结果表明,改进的Sol-gel法制得的光催化剂具有明显的孔结构,而且比表面积大、孔径分布窄、粒径小、分散性好;适量B的掺杂能够有效促进TiO₂纳米粒子的光催化活性.最佳催化剂制备条件:B掺杂的摩尔分数为20%、450℃煅烧2 h,此时所制得的B-TiO₂光催化剂活性比纯TiO₂有显著提高.     

Synthesis of W‐doped TiO2 by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

A series of tungsten‐doped Titania photocatalysts were synthesized using a low‐temperature method. The effects of dopant concentration and annealing temperature on the phase transitions, crystallinity, electronic, optical, and photocatalytic properties of the resulting material were studied. The X‐ray patterns revealed that the doping delays the transition of anatase to rutile to a high temperature. A new phase W_yTi_1‐yO₂ appeared for 5.00 wt% W‐TiO₂ annealed at 900 °C. Raman and diffuse reflectance UV–Vis spectroscopy showed that band gap values decreased slightly up to 700 °C. X‐ray photoelectron spectroscopy showed that surface species viz. Ti³⁺, Ti⁴⁺, O^2?, oxygen‐vacancies, and adsorbed OH groups vary depending on the preparation conditions. The photocatalytic activity was evaluated via the degradation of methylene blue using LED white light. The degradation rate was affected by the percentage of dopants. The best photocatalytic activity was achieved with the sample labeled 5.00 wt% W‐TiO₂ annealed at 700 °C.     

N掺杂空心TiO2微球的合成与表征

采用无皂乳液聚合合成的聚苯乙烯(PS)微球为模板、氨水/三乙醇胺为催化体系, 通过溶胶-凝胶方法合成了PS/TiO₂(核/壳)复合微球, 然后通过煅烧制备了N掺杂、锐钛型空心TiO₂微球. 在反应体系中三乙醇胺扮演双重角色, 既是TiO₂生成及包覆过程的抑制剂又是空心TiO₂微球的N掺杂剂. 改变氨水、三乙醇胺和钛酸正丁酯用量可控制TiO₂壳的形态和尺寸. 氨水用量增加, PS/TiO₂复合微球的壳表面变得粗糙|三乙醇胺用量增加, 壳表面变得光滑|钛酸正丁酯用量提高导致壳层变厚. 改变三乙醇胺用量可调节空心TiO₂微球中的N掺杂量|N掺杂空心TiO₂微球具有可见光响应和光催化作用.     

Ag/TiO2中空纳米纤维光催化材料的制备及表征

以棉花纤维为模板制备了银掺杂的TiO₂中空纳米纤维光催化材料, 利用热重分析(TG)、扫描电子显微镜(SEM)、X光电子能谱(XPS)、X射线衍射(XRD)、Zeta电位、紫外-可见光谱(UV-Vis)和傅立叶变换红外光谱(FT-IR)等技术对该材料的形貌、晶体结构、银的状态等特性进行了表征. 以亚甲基蓝(MB)的脱色降解为模型反应, 考察了银掺杂的样品Ag/TiO₂在不同光源下的光催化性能. 结果表明, 所制得的Ag/TiO₂材料保留了棉花纤维的形貌, 且表面带有大量的负电荷|该Ag/TiO₂材料在太阳光条件下的光催化性能显著高于同条件下TiO₂和同材料在紫外光条件下的, 如Ag/TiO₂在太阳光下1.5 h可使MB溶液的脱色降解率在95%以上, 在TiO₂上2.5 h时不足60%, 低于Ag/TiO₂上0.5 h的结果|在紫外光条件下Ag/TiO₂ 3 h时脱色降解率仅为35%. 连续重复使用5次时Ag/TiO₂仍能保证MB溶液的脱色降解率在90%以上|该纤维光催化材料易于离心分离去除、再利用. 因此, 以棉花为模板制备的Ag/TiO₂中空纳米纤维催化材料是一种无能耗、无污染、高活性的绿色环保型光催化材料.     

Photocatalytic Activity of TiO2 Nanofibers with Doped La Prepared by Electrospinning Method

La‐TiO₂ nanofibers are prepared by a sol‐gel assisted electrospinning method. The structure and morphology of La‐TiO₂ nanofibers are characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis shows that the weight percentage of anatase and rutile in the 1.5 mol% La‐TiO₂ nanofibers calcined at 600 °C is about 8:2, which is similar to P‐25. The XRD data of La‐TiO₂ nanofibers with different La content shows that La³⁺ dopant has a great inhibition on TiO₂ phase transformation. The photocatalytic activity of the as‐prepared La‐TiO₂ nanofibers is evaluated by photocatalytic decolorization of Methylene Blue (MB) aqueous solution. The results show that the 1.5 mol% La‐TiO₂ nanofibers calcined at 600 °C exhibit high photocatalytic activity, indicating that 600 °C and 1.5 mol% are the appropriate calcination temperature and optimal molar ratio of La to Ti, respectively.     

Preparation and Photocatalytic Activity of TiO2 Films on Silica Glass Substrates by Assembly Technique

Nanostructured TiO₂ coating films on silica glass substrates were prepared by the assembly technique. TiO₂ colloids were synthesized employing the sol‐gel method using TiCl₄ as a precursor. The effect on the surface structures which was caused by the polyethylene glycol (PEG) added to the precursor solution and the photocatalytic activity were studied. The experimental results showed that the cobble‐like TiO₂ coating films were synthesized at 500 °C. On the surface of the samples, TiO₂ films exhibited uniform shape and a narrow size distribution. The result of proper PEG added to the precursor solution led to the decreasing of the size of TiO₂ particles and the increasing of the surface area of the samples. The photocatalytic activity of TiO₂ films with PEG was higher than that of samples without PEG.     

Preparation and Characterization of K6ZrW11O39Sn‐TiO2 Composite Catalyst for Solar Photocatalytic Degradation of Aqueous Dye Solutions

A novel photocatalyst, K₆ZrW₁₁O₃₉Sn ^.12H₂O (ZrW₁₁Sn ), was synthesized in our previous study. However, the utilization of ZrW₁₁Sn was extremely limited because of its high solubility in water. A novel composite catalyst, ZrW₁₁Sn‐TiO₂ , was synthesized and characterized in this study. ZrW₁₁Sn‐TiO₂ is of nanometer‐scale and has a structure similar to that of anatase TiO₂ . The forbidden energy zone of ZrW₁₁Sn‐TiO₂ is less than that of the synthesized pure TiO₂ , while its specific surface area is larger. The photocatalytic activities of ZrW₁₁Sn‐TiO₂ were evaluated by its degradation of monoazo, disazo, anthraquinone, and three aryl methane dyes with solar irradiation in heterogeneous aqueous solutions. Results indicate that ZrW₁₁Sn‐TiO₂ has higher photocatalytic activity than the synthesized pure TiO₂ , commercial anatase TiO₂ , H₃PW₁₂O₄₀ , and H₄SiW₁₂O₄₀ doped TiO₂ . The optimum doping concentration of ZrW₁₁Sn and the calcination temperature were 1.8 wt % (ZrW₁₁Sn ) and 400°C, respectively. ZrW₁₁Sn‐TiO₂ showed a considerably high photocatalytic stability. When a Reactive Black 5 solution (200 mL , 10 mg/L; initial pH 6) with ZrW₁₁Sn‐TiO₂ (0.2 g/L) was irradiated for 60 min with simulated sunlight, the decoloration rate was >98% even after four cycles. ZrW₁₁Sn‐TiO₂ exhibited a better settling property than commercial TiO₂ , which made further separation treatment easier.     

一步火焰辅助热解法制备Fe掺杂嵌碳TiO2及其光催化性能

以钛酸四丁酯、无水乙醇和无水氯化铁为前驱体,通过一步火焰辅助热解法制备了Fe掺杂嵌碳TiO₂,并研究了样品的光催化活性. 利用扫描电子显微镜及能谱、X射线光电子能谱、X射线粉末衍射和紫外-可见漫反射吸收光谱等对样品的形貌、组分、晶型和光吸收进行了表征,并研究了样品在紫外和可见光下的光催化活性. 结果表明,无需后续热处理可直接得到主要是锐钛矿相TiO₂的样品,Fe³⁺以替位掺杂形式进入TiO₂晶格,随掺杂量增加,样品在可见光区域的吸光度提高,吸收带边红移. Fe掺杂量（摩尔分数）小于0.2%可改善样品的光催化活性,当Fe掺杂量为0.1%时,样品在可见光和紫外-可见光照射下均显示出最高的降解亚甲基蓝速率.     

Preparation of P(MBA‐co‐MAA)/Zr(OH)4/P(EGDMA‐co‐MAA)/TiO2 Tetra‐layer Hybrid Microspheres and the Corresponding ZrO2/TiO2 Double‐shelled Hollow Microspheres

Double‐shelled zirconia/titania (ZrO₂/TiO₂) hollow microspheres were prepared by the selective removal of the polymer components via the calcination of the corresponding tetra‐layer poly(N,N′‐methylenebisacryl amide‐co‐methacrylic acid) (P(MBA‐co‐MAA))/Zr(OH)₄/poly(ethyleneglycol dimethacrylate‐co‐methacrylic acid) (P(EGDMA‐co‐MAA))/TiO₂ hybrid microspheres. These tetra‐layer microspheres were synthesized by the combination of the distillation copolymerization of N,N(‐methylenebisacryl amide‐co‐methacrylic acid (MBA) or ethyleneglycol dimethacrylate (EGDMA) crosslinker and methacrylic acid (MAA) for the preparation of polymer core and third‐layer as well as the controlled sol‐gel hydrolysis of inorganic precursors for the construction of zirconium hydroxide (Zr(OH)₄) and titania (TiO₂) layers. The thicknesses of zirconia and titania shell‐layers were conveniently controlled via varying the feed of zirconium n‐butoxide (Zr(OBu)₄) and titanium tetrabutoxide (TBOT) during the sol‐gel hydrolysis, while the sizes of polymer layers were tuned through a multi‐stage distillation precipitation copolymerization. The structure and morphology of the resultant microspheres were characterized by transmission electron microscopy (TEM), X‐ray diffractometer (XRD), X‐ray photoelectronic spectroscopy (XPS), and thermogrametric analysis (TGA).