Preparation and characterization of SiO2/TiO2 composite microspheres with microporous SiO2 core/mesoporous TiO2 shell

SiO₂/TiO₂ composite microspheres with microporous SiO₂ core/mesoporous TiO₂ shell structures were prepared by hydrolysis of titanium tetrabutylorthotitanate (TTBT) in the presence of microporous silica microspheres using hydroxypropyl cellulose (HPC) as a surface esterification agent and porous template, and then dried and calcined at different temperatures. The as-prepared products were characterized with differential thermal analysis and thermogravimetric (DTA/TG), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption. The results showed that composite particles were about 1.8 μm in diameter, and had a spherical morphology and a narrow size distribution. Uniform mesoporous titania coatings on the surfaces of microporous silica microspheres could be obtained by adjusting the HPC concentration to an optimal concentration of about 3.2 mmol L⁻¹. The anatase and rutile phase in the SiO₂/TiO₂ composite microspheres began to form at 700 and 900 °C, respectively. At 700 °C, the specific surface area and pore volume of the SiO₂/TiO₂ composite microspheres were 552 and 0.652 mL g⁻¹, respectively. However, at 900 °C, the specific surface area and pore volume significantly decreased due to the phase transformation from anatase to rutile.     

Synthesis of nanosized TiO2/SiO2 particles using microwave processes and their photocatalytic activity on the decomposition of orange II

The nanosized titania and TiO₂/SiO₂ particles were prepared by the microwave-hydrothermal method. The effect of physical properties TTIP/TEOS ratio and calcination temperature has been investigated. The major phase of the pure TiO₂ particle is of the anatase structure, and a rutile peak was observed above 800°C. In TiO₂/SiO₂ particles, however, no significant rutile phase was observed, although the calcination temperature was 900°C. No peaks for the silica crystal phase were observed at either silica/titania ratio. The crystallite size of TiO₂/SiO₂ particles decreases as compared to pure TiO₂ at high calcination temperatures. The TiO₂/SiO₂ particles show higher activity on the photocatalytic decomposition of orange II as compared to pure TiO₂ particles.     

Synthesis and green up-conversion fluorescence of colloidal La0.78Yb0.20Er0.02F3/SiO2 core/shell nanocrystals

Water-soluble PVP-stabilized hexagonal-phase La_0.78Yb_0.20Er_0.02F₃ nanocrystals (NCs) were synthesized by hydrothermal method. The NCs were coated with a very thin silica shell, and amino groups were introduced to the surface of silica shells by copolymerization of 3-aminopropyl(triethoxy)silane. The core/shell NCs can be dispersed in ethanol and water to form stable colloidal solution. The transmission electron microscopy (TEM), selected area electron diffraction (SAED), powder X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the core/shell materials. In addition, the green up-conversion fluorescence mechanism of La_0.78Yb_0.20Er_0.02F₃/SiO₂ NCs was studied with a 980-nm diode laser as excitation source. The water solubility, small core/shell particles size, and well colloidal stability mean the green up-conversion fluorescence NCs have potential applications in bioassay.     

SiO2/TiO2-xCx/C的制备、表征及其吸附和可见光催化性能

以SiO2为成核中心,钛酸四丁酯为钛源,分别以多羟基化合物乙二醇、丙三醇、葡萄糖和聚乙烯醇为联接剂,采用水解沉淀法制备了碳掺杂和包覆的多孔SiO2/TiO2-xCx/C可见光响应型光催化剂。采用X-射线衍射(XRD)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)、傅里叶变换-红外光谱(FTIR)、比表面积(BET)和紫外-可见(UV-Vis)漫反射光谱对样品进行表征。对不同结构样品的形成机理进行了分析。以次甲基蓝(MB)溶液为模拟废水,对样品的吸附性能和可见光催化性能进行了评价。结果表明,多羟基化合物对材料的结构和性能有重要影响。碳的掺杂和包覆使材料的吸收光谱包含了整个可见光区,而多孔结构使材料的吸附性能得到提高。以聚乙烯醇为原料所得样品吸附性能最好,30 min内吸附率达到70%;而以丙三醇为原料所得样品具有最好的可见光催化性能,40 min内次甲基蓝的降解率达到95%。     

Monolayer oxide catalysts from alkoxide precursors, part IV. Vanadia, titania and stibia on SiO2, SnO2, and TiO2 in 2-propanol oxidation

Vanadia monolayer catalysts supported on SnO₂, ZrO₂, TiO₂, and SiO₂, similarly as titania and stibia monolayers deposited on SiO₂, have been synthesized by reacting the corresponding metal alkoxides with hydroxyls on the carrier surfaces. The metal ions loads in monolayer systems were determined. The catalysts activity was tested in 2-propanol transformations. The nature of carrier has a strong influence on the dehydrating to dehydrogenating activity ratio of vanadia monolayer.     

可磁分离二氧化钛光催化剂的制备及其光催化性能

通过液相催化相转化的方法制备了一种可磁分离的光催化剂TiO₂/SiO₂/NiFe₂O₄(TSN),这种光催化剂显示出了超顺磁性,能够通过外加磁场方便的实现催化剂在水中的分离与回收。该光催化剂的X-射线衍射和TEM结果表明：纳米TiO₂颗粒包裹在磁性颗粒-SiO₂/NiFe₂O₄(SN)的周围形成TiO₂层。利用光催化降解甲基橙的效果来考察了这种光催化剂的活性,结果表明：在NiFe₂O₄和TiO₂之间包覆一层无定型的SiO₂,可以显著的提高催化剂的脱色效果,3次循环后,仍能保持良好的催化活性。     

LB技术制备SnO2-TiO2无机交替纳米薄膜

采用LB技术将SnO₂纳米粒子和TiO₂纳米粒子组装进花生酸的交替多层膜，通过热处理除去膜中的有机成分后，采用红外光谱、紫外可见光谱、X-光电子能谱、低角X-射线衍射、原子力显微镜以及扫描电子显微镜等手段对处理后的膜进行了形貌、组成和结构表征，表明制得的是SnO₂纳米粒子-TiO₂纳米粒子无机-无机交替的均匀的纳米薄膜。     

Structural characterization and photocatalytic activity of hollow binary ZrO2/TiO2 oxide fibers

The formation of hollow binary ZrO₂/TiO₂ oxide fibers using mixed precursor solutions was achieved by activated carbon fibers templating technique combined with solvothermal process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis, and infrared (IR) spectroscopy. The binary oxide system shows the anatase-type TiO₂ and tetragonal phase of ZrO₂, and the introduction of ZrO₂ notably inhibits the growth of TiO₂ nanocrystallites. Although calcined at 575 °C, all hollow ZrO₂/TiO₂ fibers exhibit higher surface areas (>113 m²/g) than pure TiO₂ hollow fibers. The Pyridine adsorption on ZrO₂/TiO₂ sample indicates the presence of stronger surface acid sites. Such properties bring about that the binary oxide system possesses higher efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane than P25 TiO₂. In addition, the macroscopic felt form for the resulting materials is more beneficial for practical applications than traditional catalysts forms.     

Synthesis and Characterization of TiO2/YFeO3 and Its Photocatalytic Oxidation of Gaseous Benzene

YFeO₃ was prepared by coprecipitation method and citric acid method, and TiO₂/YFeO₃ heterosystem photocatalysts were synthesized by loading TiO₂ sol on the surface of YFeO₃via sol-gel method. Their photocatalytic activities were evaluated by the decomposition of gaseous benzene under UV light illumination. The prepared photocatalysts were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy. Results revealed that the heterosystem photocatalysts prepared by coprecipitation method showed higher activity, and the maximum conversion of benzene could reach 44.7% within 180 min. The YFeO₃ samples prepared from coprecipitation method and citric acid method were absolutely in orthorhombic phase. The deposited titania was dispersed on the surface of carrier and a certain interaction existed between TiO₂ and YFeO₃. The two heterosystems photocatalysts had narrow band-gap energies.     

Synthesis of SiO2/Y2O3:Eu core-shell materials and hollow spheres

The SiO₂/Y₂O₃:Eu core-shell materials and hollow spheres were first synthesized by a template-mediated method. X-ray diffraction patterns indicated that the broadened diffraction peaks result from nanocrystals of Y₂O₃:Eu shells and hollow spheres. X-ray photoelectron spectra showed that the Y₂O₃:Eu shells are linked with silica cores by Si-O-Y chemical bond. SEM and TEM observations showed that the size of SiO₂/Y₂O₃:Eu core-shell structure is in the range of 140-180 nm, and the thickness of Y₂O₃:Eu hollow spherical shell is about 20-40 nm. The photoluminescence spectra of SiO₂/Y₂O₃:Eu core-shell materials and Y₂O₃:Eu hollow spheres have better red luminescent properties, and the broadened emission bands came from the size effects of nanocrystals composed of Y₂O₃:Eu shell.     

三维有序大孔复合材料Bi2O3/TiO2制备与多模式下光催化降解结晶紫

以TiO2为基体,在聚苯乙烯(PS)胶球和EO20PO70EO20(P123)两种模板剂作用下通过溶胶-凝胶及煅烧后处理方法制备了三维有序大孔纳米复合材料Bi2O3/TiO2.经傅里叶变换红外(FT-IR)光谱、X-射线衍射(XRD)、等离子体原子发射光谱(ICP-AES)、紫外-可见漫反射吸收光谱(UV-Vis DRS)、X-射线光电子能谱(XPS)、扫描电子显微镜(SEM)和N2吸附-脱附等物理测试手段对其组成、结构、形貌及表面物理化学性能进行了表征.结果表明,该复合材料晶型结构良好,孔结构排列整齐有序,孔壁呈介孔结构,属于三维有序大孔材料(3DOM).与TiO2相比,3DOM-Bi2O3/TiO2对光的吸收至少红移60 nm,且红移至可见区.在紫外光、可见光以及微波辅助等多模式光催化降解结晶紫的实验中,复合材料3DOM-Bi2O3/TiO2表现出良好的光催化活性,其活性明显高于P25、Bi2O3和Bi2O3/TiO2.同时,该复合材料针对不同类型的染料均表现出较好的紫外光降解效果,且3次循环实验后,依旧保持较高活性.     

静电自组装制备纳米TiO2/SiO2光催化材料

采用静电自组装方法制备了纳米TiO2/SiO2光催化材料。采用巯丙基三甲氧基硅烷偶联剂对SiO2进行干法改性,采用双氧水/冰醋酸将偶联剂巯基基团氧化为磺酸基基团。在正负电荷的吸引下,带负电荷的SiO2与带正电荷的钛聚合阳离子自发地组装在一起,经一定温度热处理得到纳米TiO2/SiO2光催化材料。采用XRD、FTIR、PL、UV-Vis DRS、SEM和ICP等对材料进行了分析和表征。采用甲基橙溶液评价材料的光催化性能。结果表明:SiO2促使锐钛矿的形成,抑制锐钛矿向金红石的转变,减小TiO2的晶粒尺寸,使得TiO2光吸收波长发生蓝移。TiO2与SiO2通过Si-O-Ti键发生结合。采用静电自组装方法制备的材料中TiO2的含量高于传统方法,导致材料的光催化性能有所提高。     

ZrO4/SiO2-Al2O3催化肉桂醛MPV转移加氢性能

以九水合硝酸铝（Al（NO₃）₃·9H₂O）与正硅酸乙酯（TEOS）为前驱盐,采用溶胶-凝胶法制备一系列不同Al₂O₃含量的SiO₂-Al₂O₃复合氧化物,并通过浸渍硝酸氧锆引入ZrO₂,制备ZrO₂/SiO₂-Al₂O₃复合氧化物催化剂,考察催化剂在肉桂醛（CAL）MPV转移加氢中的催化性能,并结合N₂物理吸附、X射线粉末衍射（XRD）、傅里叶变换红外光谱（FTIR）、NH₃-程度升温脱附（NH₃-TPD）、Py-原位红外（Py-IR）等技术,研究催化剂结构、织构以及表面性质与其催化性能间的构效关系.研究表明,所制备的催化剂均以L酸为主,并含有少量B酸中心,这使得加氢产物以肉桂醇（COL）为主,并含有少量1-苯丙烯-2-丙基醚（CPE）.Al₂O₃含量不仅影响催化剂表面的酸中心数量,而且对催化剂的织构参数有较大影响.随Al₂O₃含量的增加,催化剂表面L酸与B酸中心均有所增加,而孔径则持续变小,这使得催化反应呈现CAL转化率先增加后减少、目标产物COL选择性先稍有减小后有所增加的趋势.在Si/Al比为2时,催化剂具有最优的催化性能,优化反应条件下,CAL转化率达96%,目标产物COL选择性达90%.     

系列硅铝比纳米薄层ZSM-5分子筛的合成和表征

以自制不对称双子季铵盐表面活性剂为模板, 在水热合成体系中控制合成系列硅铝比纳米薄层ZSM-5分子筛.采用X射线衍射(XRD)、N₂吸附-脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)和²⁷Al魔角旋转核磁共振(²⁷Al MAS-NMR)对合成的样品进行了表征. 详细研究了晶化温度、晶化时间、结构导向剂(SDA)用量、碱度等对合成的影响和纳米薄层ZSM-5分子筛的形成过程. 结果表明: 分子筛硅铝比越高, 结构导向剂用量越大, 所需的晶化时间越短; 晶化温度越高, 晶化时间越短; 且不同硅铝比纳米薄层ZSM-5分子筛的形貌规整度、比表面积和介孔/微孔孔容比例随着硅铝比而变化.     

载有C60的TiO2纳米粒子光催化活性

以水溶性C₆₀和TiO₂粒子为前驱体,采用水热法制备了载有C₆₀的锐钛矿型TiO₂纳米粒子。应用X射线衍射、透射电子显微镜、红外光谱、紫外-可见漫反射光谱、荧光光谱对产物进行了表征。以对-硝基苯酚为模型污染物研究了产物的光催化活性,结果表明适量负载C₆₀可以提高TiO₂纳米粒子的光催化活性,C₆₀起着传输电子、促进TiO₂光生载流子分离的作用,且经7次循环使用后对-硝基苯酚的降解效率仍能达到74%。讨论了载有C₆₀的TiO₂纳米粒子光催化降解对-硝基苯酚的机理。     

超临界流体干燥法制备纳米TiO2-SnO2-SiO2复合光催化剂及其光催化性能研究

半导体多相光催化法作为一种污染治理新技术越来越受到人们的重视,在所使用的半导体光催化剂中,TiO2以无毒,催化活性高,价廉,无污染等特点,成为最具有前途的绿色环保型催化剂之一[1],但其自身具有局限性,如禁带宽度大,需在近紫外光下才能激发产生电子空穴对,对太阳光的利用率仅     

Synthesis of bimodal porous structured TiO2 microsphere with high photocatalytic activity for water treatment

In this work bimodal structured titanium dioxide (TiO₂) microsphere has been prepared from commercial TiO₂ powder and nano-sized titania gel via sol–gel spray-coating technique. Crystallization and transformation behavior of titania gel were investigated. The results revealed that the crystallization and transformation of anatase particles were substantially affected by the concentration of solvent and calcination temperature. Anatase crystallite size of 10 nm was obtained at mole ratio of solvent/precursor 50/1 and calcination temperature of 450 °C. The prepared nano-sized titania gel was embedded within the core (commercial TiO₂, P25) during the spraying process. The prepared TiO₂ microsphere was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), field emission electron microscope (FESEM) and micropore analysis. The photocatalytic activity was monitored by following the degradation of phenol with activity benchmarked against commercial P25 (Degussa). The increase of photocatalytic activity of TiO₂ microsphere was attributed to the nano-sized anatase crystallite which has been incorporated into the TiO₂ microsphere.     

MoS2/g-C3N4复合材料的制备及可见光催化性能

首先在N-甲基吡咯烷酮溶液中超声剥离得到少层的MoS₂,将其与石墨相氮化碳（g-C₃N₄）复合,制得MoS₂/g-C₃N₄复合材料。采用X射线衍射（XRD）,扫描电镜（SEM）,X射线光电子能谱（XPS）,傅里叶变换红外光谱（FTIR）,Raman光谱,紫外-可见漫反射吸收光谱（DRS）和光致荧光（PL）技术对复合材料进行表征。可见光下考察MoS₂/g-C₃N₄复合材料光催化降解罗丹明B（RhB）的活性,结果表明：将少量MoS₂与g-C₃N₄复合可明显提高光催化活性,且1%（w/w）MoS₂/g-C₃N₄复合物的光催化活性最高,可能的原因是MoS₂和g-C₃N₄匹配的能带结构,增大了界面间电荷的传输,降低了光生电子-空穴的复合,进而提高了光催化活性。     

Preparation of porous TiO2/silica composites without any surfactants

TiO₂-SiO₂ composites, with high specific surface area (up to 308 m²/g), large pore volume, and narrow distribution with average pore sizes of 3.2 nm, have been synthesized from wollastonite and titanium sulfate in the absence of any surfactants. Calcium sulfate, a microsolubility salt, plays an important role in the formation of pores in this porous TiO₂/silica composite. The microstructure and chemical composition of composite were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectrometer (XPS) and N₂ adsorption and desorption analysis. The as-prepared porous titanium dioxide-silicon dioxide composites with high specific surface area and well-crystallized anatase contents were used as an efficient photocatalyst.     

Boron and nitrogen-codoped TiO2 nanorods: Synthesis, characterization, and photoelectrochemical properties

Boron and nitrogen codoped TiO₂ nanorods (BNTRs) were synthesized via two-step hydrothermal reactions using TiN as a starting material. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscope (SEM), transmission electron microscopy and X-ray photoelectron spectroscopy techniques. The results showed that TiO₂ nanorods with the diameter of approximately 50–100 nm and the length of several micrometers were doped by the interstitial N and B. The nanorods were firstly formed in the hydrothermal synthesis of nitrogen doped TiO₂. The growing process of nanorods was observed by SEM and a most probable formation mechanism of the trititanate nanorods was proposed. The BNTRs showed a higher photocatalytic activity and a bigger photocurrent response than N–TiO₂ nanorods under visible light irradiation.