TiO2 nanoparticles in mesoporous TUD-1: synthesis, characterization and photocatalytic performance in propane oxidation

A series of TiO2-TUD-1 samples was synthesized with a variable Ti loading in the range Si/Ti = 100, 20, 2.5, and 1.6, by using a one-pot surfactant-free procedure. The materials obtained were characterized by elemental analysis; X-ray diffraction (XRD); N2 sorption measurements; high-resolution TEM (HR-TEM); 29Si NMR, UV-visible and Raman spectroscopy. As a function of increasing metal loading either isolated Ti atoms, or (above a Ti loading of approximately 2.5 wt- %) combinations of isolated Ti atoms and anatase (TiO2) nanoparticles were obtained; both were incorporated in the highly porous siliceous matrix. The photocatalytic performance of these materials was tested by studying the propane oxidation process following irradiation at lambda = 365 nm, selectively activating the anatase nanoparticles. In comparison to commercial anatase powder, TiO2 nanoparticles in TUD-1 showed high photochemical selectivity towards acetone, the sample with a Si/Ti ratio of 1.6 being the most selective. Size and confinement effects are consistent with the difference in performance of the TUD-1 materials and TiO2, limiting the number of electron transfers available for each propane molecule.     

One-pot synthesis of highly crystalline mesoporous TiO2 nanoparticle assemblies with enhanced photocatalytic activity

We report an unprecedented formation of mesoporous titania via a surfactant-assisted aggregating assembly of TiO(2) nanoparticles. These mesostructures possess a highly crystalline anatase phase, large and accessible pore surface area, and exhibit superior photocatalytic performance.     

Novel synthesis of high-surface-area ordered mesoporous TiO2 with anatase framework for photocatalytic applications

Ordered mesoporous TiO₂ materials with an anatase frameworks have been synthesized by using a cationic surfactant cetyltrimethylammonium bromide (C₁₆TMABr) as a structure-directing agent and soluble peroxytitanates as Ti precursor through a self-assembly between the positive charged surfactant S⁺ and the negatively charged inorganic framework I^? (S⁺I^? type). The low-angle X-ray diffraction (XRD) pattern of the as-prepared mesoporous TiO₂ materials indicates a hexagonal mesostructure. XRD and transmission electron microscopy results and nitrogen adsorption–desorption isotherms measurements indicate that the calcined mesoporous TiO₂ possesses an anatase crystalline framework having a maximum pore size of 6.9 nm and a maximum Brunauer–Emmett–Teller specific surface area of 284 m² g^?1. This ordered mesoporous anatase TiO₂ also demonstrates a high photocatalytic activity for degradation of methylene blue under ultraviolet irradiation.     

Solvothermal synthesis of well-defined TiO(2) mesoporous nanotubes with enhanced photocatalytic activity

High efficiency TiO(2) photocatalyst in porous nanotubes were prepared by solvothermal alcoholysis of TiOSO(4) in the presence of carbon nanotube template.     

Enhanced photocatalytic hydrogen production performance of pillararene-doped mesoporous TiO2 with extended visible-light response

Pillararenes are a new type of supramolecular hosts,and they have been widely applied in drug delivery,catalysis,separation process,and sensors.However,they have rarely been used to produce hydrogen.Here,we report that pillararenes were used as functional molecules to explore photocatalysts and efficiently promoted hydrogen production from water.The most common and easily synthesized pdimethoxy pillar[5]arene（PI-OMe） was employed to form an organic-inorganic hybrid material with titanium dioxide...     

Samarium-doped mesoporous TiO2 nanoparticles with improved photocatalytic performance for elimination of gaseous organic pollutants

Mesoporous TiO₂ doped with different amounts of Sm were prepared via a sol-gel route with Pluronic P123 as template. The materials were characterized by X-ray diffraction, transmission electron microscopy, and N₂ sorption experiments, etc. The photocatalytic activity of the mesoporous TiO₂ was tested in elimination of gaseous methanol and acetone. The Sm doped mesoporous TiO₂ have higher activity than those of the commercial photocatalyst (Degussa, P25) and Sm doped TiO₂ counterparts without mesopore structure under ultraviolet light irradiation. A possible mechanism was proposed to account for the high photocatalytic activity of the Sm doped mesoporous TiO₂. The superior activity of the Sm doped mesoporous TiO₂ may be attributed to the synergic effect of the high surface area, mesopore structure and doped Sm species.     

Preparation of upconversion Yb3+ doped microspherical BiOI with promoted photocatalytic performance

Bismuth oxychloride (BiOI) has a good visible light responsive property due to their relatively narrow band gap, and its photocatalytic performance was further improved by doping ytterbium ions (Yb³⁺). This may be due to strong optical absorption in UV–visible light, effective separation of the photoinduced electron-hole pairs, and the capacity to up-convert Near-IR light into visible-light of Yb³⁺ ions. In this study, a facile solvothermal method was adopted to synthesize Yb³⁺ ions doped BiOI photocatalysts. The doped photocatalysts with molar ratios of 0, 0.5, 1, 1.5, 2 and 2.5% Yb³⁺ ions were prepared. The 2% Yb³⁺ ions doped BiOI exhibited the highest photocatalytic degradation efficiency on degrading Rhodamine B, which was two times higher than that of pure BiOI. Also Yb³⁺ ions doped BiOI showed high photocatalytic degradation on herbicide isoproturon. The prepared photocatalysts were characterized by SEM, XRD, UV–vis DRS. It indicated that the doping ions entered the lattice of BiOI crystals and improved the photocatalytic performance. The photocatalytic mechanism was also studied. This work provided the potential application of Yb³⁺ doped BiOI for the degradation of organic contaminants.     

Microemulsion-mediated sol-gel synthesis of mesoporous rutile TiO2 nanoneedles and its performance as anode material for Li-ion batteries

Mesoporous rutile TiO(2) nanoneedles have been successfully synthesized using a reverse microemulsion-mediated sol-gel method at room temperature. The materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and the Bruauner-Emmet-Teller (BET) adsorption method, and their electrochemical properties were investigated by galvanostatic charge and discharge tests. XRD observations revealed the formation of a pure rutile TiO(2) phase. Furthermore, TEM observation revealed the presence of a highly porous needle-like morphology. The electrochemical measurements show that the nanoneedles deliver an initial capacity of 305 mA h g(-1) as anode material for Li-ion batteries and sustain a capacity value of 128 mA h g(-1) beyond 15 cycles. The reported synthesis is simple, mild, energy efficient, and without postcalcination.     

Cerium-doped mesoporous BaTiO3/TiO2 nanocomposites: structural,optical and photocatalytic properties

Research on Chemical Intermediates - Nanoscale composite materials based on cerium, barium titanate and titanium dioxide were synthesized by thermal hydrolysis. The obtained individual TiO2, BaTiO3...     

In3+-doped TiO2 and TiO2/In2S3 nanocomposite for photocatalytic and stoichiometric degradations

A novel In(3+)-doped TiO(2) and TiO(2)/In(2)S(3) nanocomposites for photocatalytic degradation of environmental pollutants and stoichiometric degradation of warfare agents were prepared by a homogeneous hydrolysis with urea and thioacetamide, respectively. The prepared samples series TiInTAA were annealed at 600°C. The prepared samples were characterized by X-ray powder diffraction, IR spectroscopy, Raman spectroscopy, specific surface area (BET) and porosity determination. The method of UV-Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photocatalytic activity (PCA) was tested by degradation of Orange dye, whereas stoichiometric activity was studied by degradation of sulfur mustard. Incorporation of In(3+) into titania lattice increases PCA of TiO(2) in the visible light and increases stoichiometric decomposition of sulfur mustard against nondoped TiO(2) as well. PCA of TiO(2)/In(2)S(3) composite depends on the optimal ratio of TiO(2):In(2)S(3) in composite, while the activity for stoichiometric decomposition of sulfur mustards depends on the content of In(2)S(3) in nanocomposite.     

Cu2+掺杂的Bi2O3的制备及光催化性能的研究

本文采用并流沉淀法制备了Cu2+掺杂的纳米Bi2O3光催化剂(Cu/Bi原子比分别为1%,2%,3%和4%)。以甲基橙模拟有机污染物对催化剂的光催化性能进行了考察。用比表面(BET)、X-射线粉末衍射(XRD)、X-射线光电子能谱(XPS),紫外-可见漫反射光谱(DRS)和表面光电压谱(SPS)对所制备的催化剂进行了表征。结果表明,Cu2+掺杂量为3%时制备的Bi2O3具有最高的比表面积、孔容、最小孔径和晶粒尺寸。对甲基橙的光催化脱色结果显示掺杂量为3%时Cu2+-Bi2O3表现出最佳的光催化活性。     

Effect of a long-term exposure of anatase TiO2 powder doped with surface-located Sb3+ ions to UV radiation on its photocatalytic activity

Ultraviolet photocatalytic experiments on the kinetics of decolorization of methyl orange and the ¹²¹Sb Mössbauer characterization of the title catalyst were performed. The stereochemically active electronic lone pair of Sb³⁺ was found to completely deactivate the neighboring oxygen vacancy as a recombination center towards the photogenerated electrons and holes.     

Preparation and photocatalytic antibacterial property of nitrogen doped TiO2 nanoparticles

Nitrogen doped TiO₂ (N-TiO₂) nanoparticles with about 30 nm in size were produced by a sol–gel method and characterized respectively by UV–vis, X-ray diffraction (XRD), Transmission electron microscopy, X-ray photoelectron spectroscopy (XPS). Their photocatalytic antibacterial properties were evaluated by the antibacterial ratio against Escherichia coli in dark and under simulated sunlight respectively. The XRD pattern showed that the doped nano-TiO₂ was mainly composed of anatase phase. The XPS spectra of the N-TiO₂ sample indicated that TiO₂ was doped by nitrogen atom. The nitrogen doping created a new N 2p state slightly above the valence band top consists of O 2p state, and this pushes up the valence band top and decreased the band gap. Which leaded to the absorption edge was red-shifted to the visible light region of UV–vis spectra of nitrogen doped nano-TiO₂ comparing with pure nano-TiO₂. The antibacterial percentage of N-TiO₂ against E. coli reached to 90 % under simulated sunlight for 2 h, which was much better than that in dark, also than that of pure nano-TiO₂. The photo-catalytic antibacterial activity was activated under visible light. The structure and integrity of cell wall and cell membrane were destructed, and even caused the bacteria death.     

S掺杂的还原态TiO2-x的制备及其可见光催化性能

作为一种稳定、价廉的光催化剂,TiO2被广泛应用于各种污染物的降解;但是,较大的宽禁带(~3.2 eV)和较低的电子迁移率不仅使TiO2很难吸收可见光,而且光生电子和空穴的复合几率高,从而导致TiO2的总体光电效率不高.因此,设计能够被可见光激发、并具有快速光生电子传输的TiO2一直是研究热点.研究表明,Ti3+自掺杂的TiO2(还原态TiO2-x)不仅能够被可见光激发,而且使TiO2具有良好的电子导电性,从而有利于提高TiO2的光电转换效率.另外,非金属元素的掺杂能够减小TiO2的禁带宽度,使TiO2能够响应可见光并具有良好的可见光催化性能,其中S元素的掺杂被广泛研究.目前,S掺杂纳米TiO2的制备通常采用TiS2,单质S,硫脲、二甲亚砜等为S源,但这类原料通常价格昂贵或者具有一定的毒性,因而实际应用受到限制.而制备Ti3+自掺杂TiO2的方法大都是基于"还原法",在真空或强还原性气氛如H2,CO中加热TiO2,或采用高能粒子(电子、氩离子)轰击.在实际应用中,这些方法存在步骤多、条件苛刻、反应时间长和设备昂贵等不足.而且,还原法反应通常发生在颗粒的表面,形成的Ti3+很容易被空气和水中的溶解O2氧化,降低材料的稳定性.虽然在温和的液相中还原Ti4+可用于制备Ti3+掺杂的TiO2,但是由于反应过程中有副产物生成,需要进行后续处理才能得到纯的Ti3+自掺杂TiO2.因此,设计一种简单的制备S掺杂还原态TiO2-x光催化剂仍具有十分重要的意义.前期我们采用H2O2氧化TiH2得到不同状态的前驱体凝胶,然后进行不同方式的后处理得到Ti3+自掺杂的纳米TiO2.本文以TiH2和H2O2反应得到的黄色前驱体凝胶为Ti源,以价格低廉、无毒、稳定的二氧化硫脲为S源和还原剂,采用不同的方法制备了S掺杂的还原态TiO2-x光催化剂.本文初步研究了在凝胶中加入二氧化硫脲后进行水热处理,以及将干燥的凝胶粉末与二氧化硫脲混合热处理对所得产物的影响.并与纯的TiO2、还原态TiO2-x和S掺杂TiO2的光吸收、电化学、光催化性能进行对比研究.采用X射线衍射、透射电子显微镜、高分辨透射电子显微镜、X-射线光电子能谱、紫外-可见漫反射光谱、比表面分析和电化学工作站等技术对产物的结构、形貌和光电性能进行了表征.以罗丹明B(RhB)溶液为模拟废水,考察样品的可见光催化性能.结果表明,不同的后续处理方式不仅影响S掺杂TiO2-x的结晶性和形貌,而且影响产物的光吸收性能和电子传输性能,从而使不同条件下所得产物的可见光催化性能不同.其中,采用热处理方式得到的S掺杂TiO2-x样品在可见光下降解RhB的速率分别是纯的TiO2,TiO2-x和S掺杂TiO2的31,2.5和3.6倍,而且样品具有良好的循环稳定性.     

原位合成稳定的Ti3+自修饰介孔TiO2光催化剂在环境净化中的应用

半导体光催化剂TiO2因具有绿色环保无污染、化学稳定性好及可实现稳定产氢等优点而广泛应用于光解水、废水处理和空气净化等领域.然而,锐钛矿相TiO2禁带宽度约为3.2 eV,仅对紫外光响应.而在太阳光中,44%左右为可见光,紫外光仅占不到4%.为了提高TiO2对太阳光的利用率和在可见光照射下的光催化活性,近年来人们采用掺杂金属/非金属离子以及与可见光催化剂复合等方法对TiO2进行改性.但是这些离子掺杂的方法会不可避免地在TiO2晶格中形成结构缺陷,这些结构缺陷作为光生电子和空穴的复合中心不利于电子和空穴分离.最近研究表明,通过Ti3+自掺杂可以很好提高TiO2可见光催化活性,但是目前制备Ti3+掺杂TiO2的方法较复杂,形成的Ti3+掺杂易在表面积聚而被进一步氧化,影响其光催化稳定性,不利于实际应用.因此,开发具有良好电子-空穴分离效率的可见光催化剂引起了广泛的研究兴趣.本文通过原位自掺杂Ti3+来提高TiO2可见光光催化活性.以TiCl3为钛源, H2O为溶剂, F127为软模板,采用溶剂挥发诱导自组装的方法制备了蠕虫状Ti3+自掺杂的介孔TiO2.采用X射线衍射(XRD)、N2物理吸附、紫外-可见漫反射(UV-vis)、透射电子显微镜和电子顺磁共振(EPR)对所制备样品结构、结晶度和形貌等进行了表征分析.通过控制表面活性剂用量和焙烧温度优化了Ti3+自掺杂介孔TiO2的光催化活性.结果表明,在模拟太阳光照射下,所制样品对气相光催化氧化NO和水相降解有机染料亚甲基蓝表现出优异的催化性能和稳定性. Ti3+自掺杂介孔TiO2有效扩展了催化剂的光吸收范围,提高了光生电子空穴的迁移效率.其优异的光催化活性和稳定性主要归因于掺杂在TiO2骨架中的Ti3+和所合成催化剂多孔性之间的协同效果.固体UV-vis结果表明,所合成的TiO2具有很好的可见光响应,主要归因于在TiO2材料合成过程中,部分Ti3+未被完全氧化, Ti3+掺入可以有效降低TiO2的禁带宽度.通过计算可知合成的TiO2禁带宽度为2.7 eV.通过低温EPR测试进一步证明了Ti3+的存在,而且Ti3+主要掺杂在TiO2体相中. N2物理吸附结果表明,随焙烧温度不断提高,所得产物的比表面积先增加后减少,当焙烧温度在500 oC时,比表面积最大,但至550 oC时,比表面积、孔径和孔体积增大,表明催化剂的孔结构被破坏.表面活性剂F127的用量对样品比表面积和孔径大小也有影响,当其用量为0.54 g时,所得产物的比表面积最大.我们将所合成的TiO2应用于污染气体NO的氧化,考察了焙烧温度和表面活性剂用量对光催化剂性能的影响.结果表明,当表面活性剂用量为0.54 g,焙烧温度为500oC时,所制催化剂在模拟太阳光和可见光照射下都表现出最好的NO去除转化率.将使用过的催化剂离心洗涤后进行连续反应3.5 h,依然保持很高的NO去除转化率.催化剂高活性及稳定性的主要原因是Ti3+的掺杂将TiO2光响应范围拓展到可见光区域,且Ti3+掺杂和介孔结构之间的协同作用有利于促进光生电子和空穴的分离.当催化剂在低于500 oC焙烧时,所得催化剂结晶度较低,不利于光生电子-空穴的分离,而高温焙烧则会导致催化剂介孔结构遭到破坏,不利于NO气体吸附和产物脱附.表面活性剂对催化剂活性影响较小,在可见光照射下催化剂均表现出很好的光催化活性.此外,该Ti3+自掺杂介孔TiO2在液相条件下对有机染料亚甲基蓝也表现出很好的去除效果,可见光照射2 h,亚甲基蓝去除率接近100%.     

Vacuum-activated Co2+ and Ti3+ co-modified TiO2 with stable and enhanced photocatalytic activity

Research on Chemical Intermediates - Vacuum-activated method was used to prepare Co2+ and Ti3+ co-modified TiO2 with the intention of enhancing visible light photo-catalytic performance, by...     

A mesoporous Pt/TiO2 nanoarchitecture with catalytic and photocatalytic functions

A novel metal/semiconductor nanocomposite with catalytic and photocatalytic functions has been prepared. The new material consists of highly dispersed platinum (Pt) nanoparticles embedded in a cubic mesoporous nanocrystalline anatase (meso-nc-TiO2) thin film. The porous thin film possesses a narrow pore-size distribution and a large surface area. The diameter of the Pt cluster can be controlled to below 5 nm, and the high dispersion of these clusters gives rise to catalytic activity for the oxidation of carbon monoxide, an important reaction for automobile exhaust treatment. This novel ordered mesoporous Pt/TiO2 nanoarchitecture is also a promising photochemical material, as demonstrated by the photo-driven killing of Micrococcus lylae cells on the film.     

C/Nd/TiO2催化剂的制备及光催化性能研究

利用溶胶-凝胶法以钛酸四丁酯为钛源、硝酸钕为钕源、葡萄糖为碳源,制备了C和Nd单掺杂及共掺杂TiO_2催化剂。通过XRD、XPS、漫反射、SEM和物理吸附对所制备的催化剂进行表征与评价。结果表明,C和Nd共掺杂TiO_2的晶型仍为锐钛矿型,表面光滑,晶粒大小分散均匀,孔径分布在20~34 nm之间;与其他三种催化剂相比,共掺杂催化剂比表面积较大;通过掺杂C和Nd元素,形成新能带E_(C2p)和E_(Nd3+4f),降低了电子跃迁能,有利于光催化活性增强。C和Nd共掺杂TiO_2对可见光的吸收能力有明显提高,对甲基橙染料降解效果较佳,其脱色率为61.24%。     

Preparation of mesoporous TiO2/CNT nanocomposites by synthesis of mesoporous titania via EISA and their photocatalytic degradation under visible light irradiation

Stabilized mesoporous TiO₂ was synthesized by evaporation induced self assembly (EISA) method and mechanically incorporated into single-walled carbon nanotubes (SWCNT) with different ratios. The physicochemical properties of the nanocomposites (mesoporous TiO₂/SWCNT) materials were investigated by Brunauer–Emmett–Teller (BET) measurement, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), photoluminescence (PL) and ultraviolet–visible (UV–Vis) spectroscopy measurements. The catalytic activity of mesoporous TiO₂ and nanocomposites were assessed by examining the degradation of rhodamine B as model aqueous solution under visible light. CNTs are facilitating the photocatalytic activity of mesoporous TiO₂ in the degradation of rhodamine B efficiently.     

Nitrogen-doped carbon enhanced mesoporous TiO2 in photocatalytic remediation of organic pollutants

Research on Chemical Intermediates - Controllable synthesis of mesoporous photocatalysts is of great interest for the photocatalytic remediation of organic pollutants from wastewater by sunlight....