Single Step Synthesis and Functionalization of Nano Titania for Development of Multifunctional Cotton Fabrics

Synthesis and modification of nanoparticles to make them suitable to functionalise a substrate for various application fields involves many steps, which are complex, time-consuming, and sometimes require special equipment. This is a major drawback to meet rapid technological requirements. In this work, a procedure has been developed to modify TiO2 nanoparticles by the sol-gel method at their synthesis stage using titanium tetraisopropoxide and modifying agents including ODS and GPTMS. The prepared nanoparticle finish can be used as it is without any further processing, thus eliminating the need for extra steps required to decorate them on some substrate. The nanoparticles were characterised by SEM, EDX, FTIR, XRD, and zeta potential. The adhesion of the obtained nanoparticles was tested by applying them to a cellulosic substrate. The obtained substrate was subjected to mechanical action and adhesion efficiency was estimated on the basis of UV transmittance and antibacterial properties that showed excellent results. The hydrophobic properties of the obtained nanoparticles were assessed by measuring water contact angles, which reached 157.9°, indicating their superhydrophobic nature. The developed procedure is facile and will be suitable for the engineering of multiple surfaces.

Synthesis and Photocatalytic Activity of TiO2 on Phenol Degradation

Photocatalysis is a process of accelerating reactions that are assisted by energy from light irradiation. Titanium dioxide (TiO2) is one of the most widely developed photocatalysis materials, and is used because of its high catalytic activity, stability and very affordable. The most commonly used precursors of TiO2 are titanium butoxide (TBOT) and titanium tetraisopropoxide (TTIP). These variations in precursor can lead to phase difference in the formation of TiO2 crystals, which further improves its nature in the activity of photocatalysis. In this study, the sol-gel method was used to synthesize titanium dioxide nanoparticles from variations of TBOT and TTIP. Furthermore, the structure, crystallite size and band gap of TiO2 were determined by X-ray diffraction (XRD) and UV-vis reflectance spectroscopy (DRS). Subsequently, TiO2 photocatalytic activity was evaluated in phenol photodegradation as a contaminant model with UV irradiation. The results showed the structure synthesized from TBOT had a higher amount of anatase, higher crystallinity, smaller crystallite size, larger band gap, and better photocatalytic activity than those from TTIP. Furthermore, it was shown that TiO2 from TBOT had an efficiency of 147% greater than TiO2 P25 Degussa, while TiO2 from TTIP had 66% efficiency compared to TiO2 P25.

Using In Situ Measurements to Experimentally Characterize TiO2 Nanoparticle Synthesis in a Turbulent Isopropyl Alcohol Flame

The objective of the present work is to show the potential of in situ measurements for the investigation of nanoparticles production in turbulent spray flames. This is achieved by considering multiple diagnostics to characterize the liquid break-up, the reactive flow and the particles production in a spray burner for TiO2 nanoparticle synthesis. The considered liquid fuel is a solution of isopropyl alcohol and titanium tetraisopropoxide (TTIP) precursor. Measurements show that shadowgraphy can be used to simultaneously localize spray and nanoparticles, light scattering allows to characterize the TiO2 nanoparticles distribution in the flame central plane, and spontaneous CH* and OH* chemiluminescences, as well as global light emission results, can be used to visualize the reactive flow patterns that may differ with and without injection of TTIP. Concerning the liquid, it is observed that it is localized in a small region close to the injector nozzle where it is dispersed by the oxygen flow resulting in droplets. The liquid droplets rapidly evaporate and TTIP is quasi-immediately converted to TiO2 nanoparticles. Finally, results show high interactions between nanoparticles and the turbulent eddies.

Preparation, Characterization and Evaluations of Carbon-Doped Ag/Fe/TiO2 Mesoporous Nanocomposite Photocatalyst for Degradation of Methylene Blue and Congo Red

Carbon doped silver/iron/TiO2 nanocomposite is synthesized via the solvothermal technique. Titanium tetraisopropoxide is used as a TiO2 source. The composite samples are characterized by different physicochemical methods, including nitrogen adsorption–desorption analysis, transmission electron microscope, scanning electron microscope, X-ray diffraction, photoluminescence, UV-vis, Fourier-transform infrared, and Energy dispersive X-ray spectroscopy. The nanocrystalline structure of the samples with anatase phase having a tetragonal shape is shown by the XRD and TEM analysis. The photo-absorption boundary of pure TiO2 expands into the visible light region due to composite formation, shown by analysis of UV-vis data. An increase in the degree of electron–hole couple segregation is shown via photoluminescence analysis. N2 adsorption–desorption analysis manifests the higher surface area of samples along with mesoporous nature. The high photodegradation action is shown by the composite samples as compared to pure mesoporous TiO2.

Characterization and evaluation of the photocatalytic activity of oxides based on TiO2 synthesized by hydrolysis controlled by the use of water/acetone mixtures

New photocatalysts based on TiO2 were synthesized and characterized. The synthesis involved the controlled hydrolysis of titanium tetraisopropoxide using water containing different proportions of acetone. X-ray diffraction analyses combined with Raman spectroscopy revealed crystalline oxides characterized by the coexistence of the anatase and brookite phases. The Rietveld refinement of diffractograms showed that the presence of acetone in the synthesis process influenced the composition of these crystalline phases, with the proportion of brookite growing from 13% to 22% with the addition of this solvent in the synthesis process. The BET isotherms revealed that these materials are mesoporous with surface area approximately 12% higher than that of the oxide prepared from hydrolysis using pure water. The photocatalytic potential of these oxides was evaluated by means degradation tests using the dyes Ponceau 4R and Reactive Red 120 as oxidizable substrates. The values achieved using the most efficient photocatalyst among the synthesized oxides were, respectively, 83% and 79% for mineralization, and 100% for discoloration of these dyes. This same oxide loaded with 0.5% of platinum and suspended in a 5:1 v/v water/methanol mixture, produced 56 mmol of gaseous hydrogen in 5 h of reaction, a specific hydrogen production rate of 138.5 mmol h−1g−1, a value 60% higher than that achieved using TiO2 P25 under similar conditions.

MULTIFUNCTIONALIZATION OF A CELLULOSIC MATERIAL BY MEANS OF A MULTIPLE-STEP COATING PROCESS APPLYING ORGANOTRIALKOXYSILANES

The sol-gel process is an excellent process for coating various substrates and thus imparting new functionalities to the treated material. Cotton fabrics were finished with various silicon alkoxides: tetraethoxysilane, (3-triethoxysilylpropyl)succinic acid anhydride, and (3-glycidyloxy)propyltrimethoxysilane in a one-, two-, and three-step process, applying the pad-dry-cure method. The physico-mechanical parameters: dry crease recovery angle, tensile strength, flexural rigidity, air permeability, abrasion resistance, whiteness index (WI), and water vapor permeability of the as-prepared cotton samples were evaluated. In addition, the coated samples were analyzed by means of Fourier transform-infrared/attenuated reflection spectroscopy, thermal gravimetric analysis, and 3D laser confocal microscopy. To study the wettability, selected alkoxysilane-treated specimens were coated with octyltriethoxysilane. The impregnation with titanium tetraisopropoxide significantly increased the ultraviolet protection factor. The findings make evident that the wrinkle resistance could be improved.

Self - Cleaning Property of Ag/TiO2 Thin Film

Ag/TiO2 thin film was prepared by the sol-gel method through the hydrolysis of titanium tetraisopropoxide and silver nitrate solution. Spin coating method was used to get uniform film on ITO glass substrate followed by annealing process for 1 hour. After that, all the samples were characterised using GIXRD and FESEM and undergone water contact angle test and MB degradation. Silver ion concentrations were varied to observe the effect on crystalline state, morphology, wettability and photocatalytic properties. The results showed that Ag/TiO2 thin film was in anatase phase and it could degrade nearly 70% of methylene blue after 150 min illumination. The formed Ag/TiO2 thin film has excellent self-cleaning property with compact, continuous, smooth, and good hydrophilicity property.

Sharpless Asymmetric Epoxidation: Applications in the Synthesis of Bioactive Natural Products

: This review discusses an important synthetic tool proposed by K. B. Sharpless in 1980, known as the Sharpless asymmetric epoxidation of allylic alcohols, and examines its use in the total synthesis of representative exponents of biologically active natural products. Focus is given to the synthesis of simple to highly complex secondary metabolites, including lactones, amino acids, diterpenes, and macrolides. The Sharpless approach involves the use of a catalyst, titanium tetraisopropoxide [Ti(OiPr)4], dialkyl tartrate as chiral ligand, and tert-butyl hydroperoxide (TBHP) as oxidizing agent. The method allows converting allylic alcohols to epoxides, which are chiral building blocks and versatile intermediates in the synthesis of natural products. The biological and synthetic importance of epoxides lies in the susceptibility of the threemembered heterocyclic ring to stereo- and regioselective opening by nucleophilic or acidic reagents, providing oxygen adducts.

Effect of Annealing Temperature on Spatial Atomic Layer Deposited Titanium Oxide and Its Application in Perovskite Solar Cells

In this study, spatial atomic layer deposition (sALD) is employed to prepare titanium dioxide (TiO2) thin films by using titanium tetraisopropoxide and water as metal and water precursors, respectively. The post-annealing temperature is varied to investigate its effect on the properties of the TiO2 films. The experimental results show that the sALD TiO2 has a similar deposition rate per cycle to other ALD processes using oxygen plasma or ozone oxidant, implying that the growth is limited by titanium tetraisopropoxide steric hindrance. The structure of the as-deposited sALD TiO2 films is amorphous and changes to polycrystalline anatase at the annealing temperature of 450 °C. All the sALD TiO2 films have a low absorption coefficient at the level of 10−3 cm−1 at wavelengths greater than 500 nm. The annealing temperatures of 550 °C are expected to have a high compactness, evaluated by the refractive index and x-ray photoelectron spectrometer measurements. Finally, the 550 °C-annealed sALD TiO2 film with a thickness of ~8 nm is applied to perovskite solar cells as a compact electron transport layer. The significantly enhanced open-circuit voltage and conversion efficiency demonstrate the great potential of the sALD TiO2 compact layer in perovskite solar cell applications.