Ag‐Enhanced TiO2–x/C Composites with Metal‐Organic Frameworks as Precursors for Photodegradation of Methyl Blue

A series of Ag‐enhanced TiO_2–x/C composites (Ag/TiO_2–x/C composites) with metal‐organic frameworks (MOFs) as precursors were prepared, and their photocatalytic activities were evaluated by the UV‐light driven photodegradation behaviors of methyl blue (MB). The as‐obtained samples were characterized by several techniques such as SEM, XRD, N₂‐adsorption, XPS, UV/Vis spectrophotometry and UV/Vis diffuse‐reflectance spectra. The best photocatalytic performance was achieved in Ag/TiO_2–x/C composite pyrolyzed at 1000 °C (ATC‐P10) due to rapid capture of electrons caused by silver doping, higher density of TiO_2–x lattice oxygen vacancies for better trapping of electrons, and high surface area due to reduction and evaporation of metallic Zn. No obvious deactivation was observed after 10 cycles of UV‐light degradation of MB under the same experimental conditions. This report reveals a new approach to prepare stable and highly efficient UV‐light‐driven photocatalysts for organic pollutants in water.     

Synthesis of TiO2–SiO2/polymer core–shell microspheres with a microphase‐inversion method

A novel microphase‐inversion method was proposed for the preparation of TiO₂–SiO₂/poly(methyl methacrylate) core–shell nanocomposite particles. The inorganic–polymer nanocomposites were first synthesized via a free‐radical copolymerization in a tetrahydrofuran solution, and the poor solvent was added slowly to induce the microphase separation of the nanocomposite and result in the formation of nanoparticles. The average particle sizes of the microspheres ranged from 70 to 1000 nm, depending on the reaction conditions. Transmission electron microscopy and scanning electron microscopy indicated a core–shell morphology for the obtained microspheres. Thermogravimetric analysis and X‐ray photoelectron spectroscopy measurements confirmed that the surface of the nanocomposite microspheres was polymer‐rich, and this was consistent with the core–shell morphology. The influence of the synthetic conditions, such as the inorganic composition and the content of the crosslinking monomer, on the particle properties was studied in detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3911–3920, 2006     

TiO2–SiO2 Catalyzed Eco‐friendly Synthesis and Antioxidant Activity of Benzopyrano[2,3‐d]pyrimidine Derivatives

A cost‐effective and eco‐friendly synthesis of benzopyrano[2,3‐d ]pyrimidine derivatives has been developed via three component one‐pot tandem approach by condensing different salicylaldehydes and secondary amines with malononitrile in the presence of TiO₂–SiO₂ catalyst at 80°C under solvent‐free conditions. Mild experimental conditions, reusability of the catalyst, and cost effectiveness are the merits of this procedure. Compounds 4g , 4h , and 4i bearing 2‐OMe group on the hydroxyphenyl group linked to the central carbon present in between the two nitrogen atoms of the pyrimidine ring were found to exhibit good antioxidant activity while other compounds have moderate antioxidant activity.     

Hybrid TiO2–Ruthenium Nano‐photosensitizer Synergistically Produces Reactive Oxygen Species in both Hypoxic and Normoxic Conditions

Photodynamic therapy (PDT) is widely used to treat diverse diseases, but its dependence on oxygen to produce cytotoxic reactive oxygen species (ROS) diminishes the therapeutic effect in a hypoxic environment, such as solid tumors. Herein, we developed a ROS‐producing hybrid nanoparticle‐based photosensitizer capable of maintaining high levels of ROS under both normoxic and hypoxic conditions. Conjugation of a ruthenium complex (N3) to a TiO₂ nanoparticle afforded TiO₂‐N3. Upon exposure of TiO₂‐N3 to light, the N3 injected electrons into TiO₂ to produce three‐ and four‐fold more hydroxyl radicals and hydrogen peroxide, respectively, than TiO₂ at 160 mmHg. TiO₂‐N3 maintained three‐fold higher hydroxyl radicals than TiO₂ under hypoxic conditions via N3‐facilitated electron–hole reduction of adsorbed water molecules. The incorporation of N3 transformed TiO₂ from a dual type I and II PDT agent to a predominantly type I photosensitizer, irrespective of the oxygen content.     

Enhancement of Antibacterial Capability of Cotton Textiles Coated with TiO2–SiO2/Chitosan Using Hydrophobization

Since textiles have a porous and hydrophilic structure, they are ideal substrates for the settlement and growth of pathogenic bacteria. Therefore, fabrication of hydrophobic textiles to reduce their humidity has the potential to inhibit the growth of bacteria. On this basis, we report here an improvement of the antibacterial capability of textiles coated with TiO₂–SiO₂/chitosan using hydrophobization. Synthesis of TiO₂–SiO₂ clusters with chitosan was carried out using the sol–gel technique. In addition, hydrophobization of the textiles using hexadecyltrimethoxysilane (HDTMS) was carried out using a dip‐spin coating method. In addition, their characteristics were examined using X‐ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectra (UV‐DRS), Fourier transform infrared (FTIR), water contact angle, and antibacterial activity. XRD, SEM, UV‐DRS, FTIR, and water contact angle confirmed the physical and chemical properties of the modified textiles. In summary, the present work shows that the hydrophobization of textiles using HDTMS can enhance the antibacterial capability of cotton textiles.     

Synthesis of polytitanosiloxanes and their transformation to SiO2–TiO2 ceramic fibers

A one-pot synthesis of polytitanosiloxanes (PTS) and its transformation to SiO₂–TiO₂ ceramic fibers were investigated. PTS was prepared by the hydrolysis of tetraethoxysilane followed by the reaction with bis(2,4-pentanedionato)titanium diisopropoxide in methanol in 33–95 SiO₂ mol %. PTS was considered to be a ladder- or sheet-type polymer consisting of Si? O? Si and Si? O? Ti linkages as a main chain with pendant hydroxyl and 2,4-pentanedionato groups. SiO–TiO ceramic fibers were prepared by the pyrolysis of SiO₂–TiO₂ precursor fibers, which were prepared by the dry spinning of PTS followed by steam treatment. The tensile strength was 610 MPa for the SiO₂–TiO₂ fibers (SiO₂/TiO₂ = 20) after the pyrolysis at 700₀C. © 1994 John Wiley & Sons, Inc.     

The Properties and Activity of TiO2/beta‐SiC Nanocomposites in Organic Dyes Photodegradation

The TiO₂/beta‐SiC nanocomposites containing 0–25 wt. % of beta‐SiC were synthesized by the sol‐gel method and tested in the photodegradation of methylene blue and methyl orange water solutions. With the increase in SiC content, only a slight decrease in energy band gap was observed (3.19–3.12 eV), together with significant increase in the surface area of the catalysts (42.7–80.4 m² g^?1). In the synthesized material, the anatase phase of TiO₂ was present in the form of small agglomerates resulting from the mechanical mixing process. In the process conditions (catalyst concentration 0.5 g L^?1, initial dye concentration 100 ppm, light source 100 W UV‐Vis lamp), we have observed no signs of catalyst deactivation. The significantly higher photodegradation activity of methylene blue than methyl orange can be attributed to the preferable pH of the solution compared to pH_PZC and the cationic character of the first dye. In case of methyl orange, pH process conditions substantially limit the contact of the catalyst with the dye, as negatively charged surface of the catalysts repels the dissociated anionic dye molecules.     

TiO2的低温制备及其对有毒有机污染物的降解

溶胶水热法制备了TiO₂粉末,用X射线衍射仪(XRD)、比表面积及孔径分析仪(BET)和透射电镜(TEM)对TiO₂进行了初步表征,结果显示:纳米TiO₂主要为锐钛矿相(含板钛矿相(121)),比表面积为106.2 m²/g.在紫外光(λ≤387 nm)照射条件下,以有机染料罗丹明B(Rhodamine B,RhB)和无色小分子2,4-二氯苯酚(2,4-dichlorophenol,2,4-DCP)的紫外光(λ≤387 nm)光催化降解试验为探针反应,低温(50℃)下制备的TiO₂粉末具有较高光催化活性,对RhB和2,4-DCP有较好的降解效果.通过分析紫外-可见光谱(UV-Vis)、红外光谱(FTIR)和总有机碳(TOC)测定,发现TiO₂/UV体系能使RhB和2,4-DCP发生有效的降解,反应5 h后RhB和7 h后2,4-DCP的矿化率分别达到81.2%和86.8%.同时,采用辣根过氧化物酶(POD)、N,N-二乙基对苯二胺(DPD)分光光度法和苯甲酸荧光光度法分别测定了在降解过程中H₂O₂和羟基自由基(.OH)的变化,表明TiO₂光催化机理涉及到.OH历程.     

Shape‐ and Functionality‐Controlled Organization of TiO2–Porphyrin–C60 Assemblies for Improved Performance of Photochemical Solar Cells

Shape‐ and functionality‐controlled organization of porphyrin derivatives–C₆₀ supramolecular assemblies using TiO₂ nanotubes and nanoparticles has been achieved for the development of photochemical solar cells. The differences in the efficiency of light‐energy conversion of these solar cells are explained on the basis of the geometrical orientation of the porphyrins with respect to the TiO₂ surface and the supramolecular complex formed with C₆₀. The maximum photon‐conversion efficiency (IPCE) of 60 % obtained with TiO₂ nanotube architecture is higher than the value obtained with nanoparticle architecture. The results presented in this study show the importance of substrate morphology in promoting electron transport within the mesoscopic semiconductor film.     

Efficient Synthesis of Novel Thiazol‐2‐ylidene‐amides Using Carbonylthiourea Building Blocks

In this work, an efficient and versatile synthesis of novel thiazol‐2‐ylidene‐amides from various carbonylthiourea derivatives is described. A sequential alkylation–cyclization reaction between thioureas and propargyl bromide in the presence of DABCO in refluxing ethanol afforded 4‐methylthiazol‐2(3H)‐ylidene‐amide derivatives in good yields.     

纳米TiO2膜负载聚(3-溴噻吩)的电化学聚合和电色效应研究

本文以纳米多孔的TiO2膜为基底,通过恒电流阳极聚合的方法制备聚(3-溴噻吩) (PBrT)膜,并研究负载在纳米TiO2膜上PBrT的电致变色性能。采用原子力显微镜(AFM)对纳米TiO2膜的形貌进行表征。利用紫外吸收光谱、计时安培法、计时吸收法研究PBrT膜的电致变色性能。结果显示,沉积在纳米多孔TiO2膜上的PBrT具有更优越的电致变色性能。PBrT膜氧化态时为亮红色,还原态时为深蓝色,颜色的对比度为22%,库仑效率为70%,着色效率为191.3 cm2 C-1（还原态）,88.9 cm2 C-1（氧化态）,该聚合膜具有良好的记忆效应。PBrT/TiO2优异的电致变色性能使其成为良好的电致变色材料,在电致变色器件方面具有潜在的应用价值。     

Effect of TiO2–Ti and TiO2–TiN composite coatings on corrosion behavior of NiTi alloy

Two kinds of biocompatible coatings were produced in order to improve the corrosion resistance of nickel titanium (NiTi) alloy. A titanium oxide–titanium (TiO₂–Ti) composite was coated on NiTi alloy using electrophoretic method. After the coating process, the samples were heat‐treated at 1000 °C in two tube furnaces, the first one in argon atmosphere and the second one in nitrogen atmosphere at 1000 °C. The morphology and phase analysis of coatings were investigated using scanning electron microscopy and X‐ray diffraction analysis, respectively. The electrochemical behavior of the NiTi and coated samples was examined using polarization and electrochemical impedance spectroscopy tests. Electrochemical tests in simulated body fluid demonstrated a considerable increase in corrosion resistance of composite‐coated NiTi specimens compared to the non‐coated one. The heat‐treated composite coating sample in nitrogen atmosphere had a higher level of corrosion resistance compared to the heat‐treated sample in argon atmosphere, which is mainly due to having nitride phases. Copyright © 2014 John Wiley & Sons, Ltd.     

Nanobiocomposite Modified Carbon‐Ceramic Electrode Based on Nano‐TiO2‐Plant Tissue and Its Application for Electrocatalytic Oxidation of Dopamine

A new modified carbon‐ceramic electrode was prepared by incorporating TiO₂ nanoparticle into sol‐gel network by accompanying apple tissue. A mixture of fine graphite powder with 15 wt% of TiO₂ nanoparticle was used for the preparation of the carbon matrix and finally modification with a known amount weighted of apple tissue. The apple tissue containing polyphenol oxidase enzyme acts as molecular recognition element. The electrocatalytic oxidation of dopamine was investigated on the surface of the nanobiocomposite modified carbon‐ceramic electrode using cyclic voltammetry, chronoamperometry and amperometry techniques. Effect of pH, scan rate, TiO₂ percentage on the response of modified electrode was studied. The prepared modified electrode presented a linear range for dopamine from 5.0×10^?6 to 1.2×10^?3 M in buffered solutions with pH 7.4 by amperometry. The detection limit was 3.41×10^?6 M dopamine. The response of the modified carbon‐ceramic electrode and unmodified carbon‐ceramic electrode was compared.     

Synthesis of Organofluoro Compounds Using Methyl Perfluoroalk‐2‐ynoates as Building Blocks

This review provides an overview of several synthetic applications of methyl perfluoroalk‐2‐ynoates, leading to convenient preparation of many perfluoroalkylated compounds. The use of these important substrates in the synthesis of various five‐, six‐, and seven‐membered heterocycles, cyclopentadienes, and biphenyls is described, alongside a discussion of the mechanistic aspects of these reactions.     

Preparation of composited Nano‐TiO2 and its application on antimicrobial and self‐cleaning coatings

Composite nano‐TiO₂ with doping Fe³⁺ and Ag was prepared, and further modified by 3‐methacryloxypropyltrimethoxysilane. They were characterized by Zetasizer Nano ZS Particle and Zeta Potential Analyzer, X‐ray diffraction, UV–Vis spectrophotometer, FT–IR spectra, and transmission electron microscopy. The modified composite nano‐TiO₂ was applied to prepare multifunctional fluorocarbon coatings (FCC). Antibacterial activity of multifunctional FCC containing modified composite nano‐TiO₂ was investigated. Its photocatalytic antibacterial activity reached 92%. The influence of doping ingredients, amount of composite nano‐TiO₂, different light houses, or surface modification was discussed. The surface of FCC cannot be easily smirched by oiliness, dust or water because of hydrophobic fluorosilicone emulsion. It would be an available modern interior building coating for its remarkable photocatalytic antibacterial property as well as self‐cleaning function. Copyright © 2009 John Wiley & Sons, Ltd.     

Metal–Organic Gel Material Based on UiO‐66‐NH2 Nanoparticles for Improved Adsorption and Conversion of Carbon Dioxide

Metal–organic frameworks (MOFs) including the UiO‐66 series show potential application in the adsorption and conversion of CO₂. Herein, we report the first tetravalent metal‐based metal–organic gels constructed from Zr^IV and 2‐aminoterephthalic acid (H₂BDC‐NH₂). The ZrBDC‐NH₂ gel materials are based on UiO‐66‐NH₂ nanoparticles and were easily prepared under mild conditions (80 °C for 4.5 h). The ZrBDC‐NH₂‐1:1‐0.2 gel material has a high surface area (up to 1040 m² g^?1) and showed outstanding performance in CO₂ adsorption (by using the dried material) and conversion (by using the wet gel) arising from the combined advantages of the gel and the UiO‐66‐NH₂ MOF. The ZrBDC‐NH₂‐1:1‐0.2 dried material showed 38 % higher capture capacity for CO₂ at 298 K than microcrystalline UiO‐66‐NH₂. It showed high ideal adsorbed solution theory selectivity (71.6 at 298 K) for a CO₂/N₂ gas mixture (molar ratio 15:85). Furthermore, the ZrBDC‐NH₂‐1:1‐0.2 gel showed activity as a heterogeneous catalyst in the chemical fixation of CO₂ and an excellent catalytic performance was achieved for the cycloaddition of atmospheric pressure of CO₂ to epoxides at 373 K. In addition, the gel catalyst could be reused over multiple cycles with no considerable loss of catalytic activity.     

CuSbS2‐Sensitized Inorganic–Organic Heterojunction Solar Cells Fabricated Using a Metal–Thiourea Complex Solution

The device performance of sensitizer‐architecture solar cells based on a CuSbS₂ light sensitizer is presented. The device consists of F‐doped SnO₂ substrate/TiO₂ blocking layer/mesoporous TiO₂/CuSbS₂/hole‐transporting material/Au electrode. The CuSbS₂ was deposited by repeated cycles of spin coating of a Cu‐Sb‐thiourea complex solution and thermal decomposition, followed by annealing in Ar at 500 °C. Poly(2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)) (PCPDTBT) was used as the hole‐transporting material. The best‐performing cell exhibited a 3.1 % device efficiency, with a short‐circuit current density of 21.5 mA cm^?2, an open‐circuit voltage of 304 mV, and a fill factor of 46.8 %.     

Investigation of Electron Behavior in Nano‐TiO2 Photocatalysis by Using In Situ Open‐Circuit Voltage and Photoconductivity Measurements

The in situ open‐circuit voltages (V_oc) and the in situ photoconductivities have been measured to study electron behavior in photocatalysis and its effect on the photocatalytic oxidation of methanol. It was observed that electron injection to the conduction band (CB) of TiO₂ under light illumination during photocatalysis includes two sources: from the valence band (VB) of TiO₂ and from the methanol molecule. The electron injection from methanol to TiO₂ is slower than that directly from the VB, which indicates that the adsorption mode of methanol on the TiO₂ surface can change between dark and illuminated states. The electron injection from methanol to the CB of TiO₂ leads to the upshift of the Fermi level of electrons in TiO₂, which is the thermodynamic driving force of photocatalytic oxidation. It was also found that the charge state of nano‐TiO₂ is continuously changing during photocatalysis as electrons are injected from methanol to TiO₂. Combined with the apparent Langmuir–Hinshelwood kinetic model, the relation between photocatalytic kinetics and electrons in the TiO₂ CB was developed and verified experimentally. The photocatalytic rate constant is the variation of the Fermi level with time, based on which a new method was developed to calculate the photocatalytic kinetic rate constant by monitoring the change of V_oc with time during photocatalysis.