Photocatalytic inactivation and removal of algae with TiO<Subscript>2</Subscript>-coated materials

The capabilities of TiO₂-coated materials for the inactivation and removal of algae were investigated. As supports for TiO₂, non-woven fabric and Ni foam were chosen. To evaluate the ability of noble metal cocatalyst additions to facilitate the photocatalytic algal inhibition of TiO₂-coated materials, Pd nanoparticles were deposited on non-woven fabric-supported TiO₂ by photoelectrochemical deposition. The fabric-supported Pd/TiO₂ showed higher inhibition activity for algal growth compared to the fabric-supported TiO₂ without Pd. In addition, Ni foam-supported TiO₂ also showed high inhibition activity, both in laboratory-scale tests and open-air tests. Therefore, TiO₂-coated materials with suitable coating methods such as the use of cocatalysts or large surface area can substantially inhibit algal growth. The ability of the TiO₂-coated materials to inhibit algae correlated well with their activity for the photocatalytic decolorization of methylene blue, suggesting a nonspecific mechanism in the breakdown of cellular structures.     

A Novel Application of Nano Anticontamination Technology for Outdoor High-Voltage Ceramic Insulators

A novel application of a nano-sized titanium dioxide (TiO₂) photocatalyst for improving the performance of the ceramic insulator under contaminated conditions is proposed in this paper. The TiO₂-coated insulator was prepared by spraying a certain amount of TiO₂ sol on the ceramic insulator followed by subsequent calcination. The physical and chemical properties of the TiO₂ film were studied and their influences on the self-cleaning and electrical performances of the ceramic insulator were evaluated. Compared with the uncoated insulators, the as-prepared TiO₂-coated insulator exhibited an enhanced self-cleaning ability in a heavy polluted environment because of the excellent photo-induced catalytic performance of the TiO₂ film. Moreover, the TiO₂-coated insulators presents a flashover voltage level similar to normal ceramic insulators, and even a higher performance of wet flashover than the latter. It was proposed that the semiconducting property and the hydrophilicity of TiO₂ films could be responsible for the promoting effect on the electrical performances of the porcelain insulator. This study shows that coating TiO₂ films on the surface of insulators may have a promise in preventing pollution flashover.     

Uniform color coating of multilayered TiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> films by atomic layer deposition

Thin film optics, based on light interference characteristics, are attracting increasing interest because of their ability to enable a functional color coating for various applications in optical, electronic, and solar industries. Here, we report on the dependence of coloring characteristics on single-layer TiO₂ thicknesses and alternating TiO₂/Al₂O₃ multilayer structures prepared by atomic layer deposition (ALD) at a low growth temperature. The ALD TiO₂ and Al₂O₃ thin films were studied at a low growth temperature of 80°C. Then, the coloring features in the single-layer TiO₂ and alternating TiO₂/Al₂O₃ multilayers using both the ALD processes were experimentally examined on a TiN/cut stainless steel sheet. The Essential Macleod software was used to estimate and compare the color coating results. The simulation results revealed that five different colors of the single TiO₂ layers were shown experimentally, depending on the film thickness. For the purpose of highly uniform pink color coating, the film structures of TiO₂/Al₂O₃ multilayers were designed in advance. It was experimentally demonstrated that the evaluated colors corresponded well with the simulated color spectrum results, exhibiting a uniform pink color with wide incident angles ranging from 0° to 75°. This article advances practical applications requiring highly uniform color coatings of surfaces in a variety of optical coating areas with complex topographical structures.     

Durable UV-protective cotton fabric by deposition of multilayer TiO<Subscript>2</Subscript> nanoparticles films on the surface

Durable ultraviolet (UV)-protective cotton fabric has great application potential in outdoor cotton clothing. In this study, oppositely charged TiO₂ nanoparticles were deposited onto cotton fabric through the layer-by-layer self-assembly technique, resulting in multilayer films with UV-protective properties. The mechanism of the technology has been investigated through characterization of the structure and properties using different techniques including FTIR, UV–Vis spectroscopy, and a scanning electron microscope with an energy-dispersive X-ray spectrum. The results showed that TiO₂ nanoparticles distributed uniformly on the surface of cotton fibers. The TGA results indicated that the TiO₂ nanoparticles deposit on cotton fabrics had little effect on the thermal stability of cotton fabrics. The tensile strength and air permeability of the cotton samples were tested by a universal material testing machine and automatic ventilation instrument. The UV protection property of cotton fabric after assembled multilayer films was measured by an ultraviolet transmittance analyzer, and the laundering experiments were carried out to determine the durability of TiO₂ nanoparticles on cotton fabric. The results showed that the UV protection property of cotton fabrics after assembled TiO₂ nanoparticles was still maintained at a high level after five launderings.     

Low-temperature fabrication of TiO<Subscript>2</Subscript> film on flexible substrate by atmospheric roll-to-roll CVD

Titanium dioxide (TiO₂) thin film was fabricated using titanium isopropoxide as a precursor through an atmospheric low-temperature roll-to-roll chemical vapor deposition method. TiO₂ was deposited on the PET substrate in the temperature range of room temperature to 100°C, and the working pressure was 740 Torr. The surface morphology of TiO₂ thin film was analyzed by field emission scanning electron microscopy and a 2D surface profiler. The results revealed that the growth rate of TiO₂ film was 31 nm/min at 100°C, and it also showed that the surface is uniform and smooth. Moreover, the lowest root mean square roughness (R _q) value of 1.87 nm was obtained for TiO₂ film prepared at 100°C. The composition of TiO₂ film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The film showed very good chemical and optical properties while increasing the substrate deposition temperature. The UV–Vis spectroscopy analysis revealed that TiO₂ films exhibited excellent optical transmittance, more than 91% observed in the visible region.     

Facile fabrication approach for a novel multifunctional superamphiphobic coating based on chemically grafted montmorillonite/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-polydimethylsiloxane binary nanocomposite

In this paper, a novel multifunctional superamphiphobic coating for anticorrosion was successfully prepared on aluminum substrate via a simple spraying technique. Al₂O₃ nanoparticles were chemically grafted onto montmorillonite (MMT) nanosheets via coupling effect of NH₂-C₃H₆-Si(OC₂H₅)₃ (KH-550) and then modified by low surface energy material polydimethylsiloxane (PDMS). The ethylene tetrafluoroethylene (ETFE) composite coating with 25 wt% MMT/Al₂O₃-PDMS binary nanocomposite exhibited well-designed nano/μ structures and possessed superamphiphobicity with high contact angles towards water (164°), glycerol (158°) and ethylene glycol (155°). This coating demonstrated outstanding self-cleaning ability and strong adhesive ability (Grade 1 according to the GB/T 9286). The superhydrophobicity could be maintained after 8000 times abrasion or annealing treatment for 2 h under 350 °C. The coating still retained high water-repellence after immersion in 1 mol/L HCl (146°), 1 mol/L NaOH (144°) and 3.5 wt% NaCl (151°) solutions for 30 d. It should be noted that this superamphiphobic coating revealed excellent long-term corrosion protection with extremely low corrosion rate (4.3 × 10^?3 μm/year) and high protection performance (99.999%) after 30 d immersion in 3.5 wt% NaCl solutions based on electrochemical corrosion measurements. It is believed that such integrated functional coating could pave new way for self-cleaning and anticorrosion applications under corrosive/abrasive environment.     

Extended hydrophobicity and self-cleaning performance of waterborne PDMS/TiO<Subscript>2</Subscript> nanocomposite coatings under accelerated laboratory and outdoor exposure testing

It has been shown that incorporation of TiO₂ nanoparticles into hydrophobic coatings can show self-cleaning performance. Accelerated laboratory testing indicated that the coats retain their hydrophobic nature for an extended time period. In this paper, hydrophobic polydimethylsiloxane (PDMS)/TiO₂ nanocomposite coatings with a TiO₂ content of 0–40% were fabricated by simple blending of a PDMS dispersion with an aqueous TiO₂ nanoparticle dispersion. Their long-term hydrophobicity and self-cleaning performance were investigated both in laboratory and real-world outdoor testing. As expected, TiO₂ nanoparticle-based coatings exhibited better self-cleaning relative to the TiO₂-free PDMS control coating as measured by methylene blue degradation testing. Excellent long-term hydrophobicity was observed in accelerated weathering testing when they contained the appropriate levels of TiO₂ nanoparticles (i.e., 0–30%). However, the same PDMS/TiO₂ coatings did not show self-cleaning performance, and instead, exhibited improved dirt pickup resistance, in outdoor exposure testing. Sustained hydrophobicity was observed in outdoor exposure testing for the clear films except when TiO₂ levels were at 40%. The hysteresis of water contact angle (HWCA) significantly increased for the PDMS control coating, and water beading was lost as the film surface picked up dirt. In contrast, the TiO₂-based coatings with appropriate TiO₂ levels maintained a relatively low HWCA after outdoor exposure and no water sheeting on rainy days was observed. This result demonstrates that while photocatalytic TiO₂ nanoparticles can maintain coating hydrophobicity upon outdoor exposure, long-term self-cleaning performance in polluted environments has not yet been achieved with this type of coating under real-world conditions.     

Preparation and characterization of transparent fluorocarbon emulsion doped with antimony tin oxide and TiO2 as thermal-insulating and self-cleaning coating

A transparent thermal insulation and self-cleaning coating was prepared from a fluorocarbon emulsion doped with antimony tin oxide (ATO) and anatase TiO₂ nanoparticles. The thermal insulation and self-cleaning properties of the coating film were optimized by adjusting the amount of ATO and anatase TiO₂ nanoparticles in the fluorocarbon emulsion. The fluorocarbon coating containing 2.0 wt% ATO and 0.1 wt% TiO₂ possessed good comprehensive properties of thermal resistance, self-cleaning, weathering resistance, etc. Compared with the blank glass substrate, the mean light transmittance of the coating film only decreased by about 12% in the visible range. The temperature in the chamber covered with the coated glasses decreased 7°C lower than the common glass chamber without coating. The methyl red painted on the coating was completely faded after three days of ultraviolet irradiation, so the coating film exhibited an excellent self-cleaning property. The transparent coating with excellent thermal insulation and good self-cleaning will be developed for a potential building glass paint used for energy saving and environmental protection.     

Developments in photocatalytic antibacterial activity of nano TiO<Subscript>2</Subscript>: A review

TiO₂, which is one of the most explored materials, has emerged as an excellent photocatalyst material for environmental and energy fields, including air and water purification, self-cleaning surfaces, antibacterial and water splitting. This review summarizes recent research developments of TiO₂-based photocatalyst used for photocatalytic antibacterial applications. Several strategies to enhance the efficiency of TiO₂ photocatalyst are discussed, including doping with metal ions, noble metals, non-metals, and coupling with other materials. The mechanism of photocatalytic antibacterial activity in the presence of nano-sized TiO₂ is also discussed. The modified TiO₂ photocatalyst significantly inhibits the growth of bacterial cells in response to visible light illumination. TiO₂ photocatalysis appears to be promising as a route of advanced oxidation process for environmental remediation.     

Photocatalytic Self-Cleaning of Wool Fibers Coated with Synthesized Nano-Sized Titanium Dioxide

Nano-sized TiO₂ was successfully synthesized and deposited onto wool fibers using the sol–gel process at ambient temperature. The prepared samples were characterized using several structural, textural, and morphological techniques. The electron micrographs show formation of TiO₂ nanoparticles 10–30 nm in size. The photocatalytic activity of TiO₂-coated wool fibers was investigated through the solid-phase self-cleaning of methylene blue (MB) under UV-vis irradiation by the diffuse reflectance spectroscopy (DRS) method. The fibers' structure is not altered upon light exposure. This preparation technique can also be applied to new fabrics to create self-cleaning and UV irradiation protection properties in them.     

Preparation and antibacterial activity of Ag/TiO2-functionalized ceramic tiles

An Ag/TiO₂ coating was deposited onto glazed ceramic tiles by a sol-gel and spraying method at high temperatures. The coating was characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results showed that silver was present in rutile-TiO₂, and the temperature did not change the phase composition of the samples. The Ag/TiO₂ coating had a higher roughness than the TiO₂ coating. The tape test (D 3359–08) showed that the coatings prepared at 950 °C and 1000 °C had good adhesion to the ceramic tile substrate. The antibacterial activity of the coating was tested by photocatalytic sterilization experiments. The results showed that the Ag/TiO₂ coating had a higher antibacterial activity than the TiO₂ coating, and the sterilization efficiency of Escherichia coli, Staphylococcus aureus, Shigella, and Salmonella exceeded 99.655% under 2 h of visible light irradiation. This research provides a method to create Ag/TiO₂ coatings with good thermal resistance, adhesion, and antibacterial activity. This improves the low photocatalytic activity caused by the anatase-to-rutile transformation of TiO₂ at high temperatures and the poor adhesion at low temperatures.     

Spray pyrolysis synthesis of mesoporous TiO<Subscript>2</Subscript> microspheres and their post modification for improved photocatalytic activity

Mesoporous TiO₂ microspheres were prepared by spray pyrolysis for photocatalysis. Post modification of TiO₂ by heat treatment was performed to optimize its photocatalytic performance. First, spherical TiO₂ particles with mesoporous structure were synthesized at pyrolysis temperatures of 500, 600, and 700 °C. After characterization by XRD, SEM, and N₂ adsorption, a sample prepared at 500 °C was found to possess desirable properties for photocatalytic performance through post-modification. In methylene blue degradation, mesoporous TiO₂ microspheres synthesized at 500 °C outperformed other microspheres. Furthermore, samples obtained by spray pyrolysis at 500 °C were calcined at various temperatures as a post-modification process. The sample calcined at 350 °C showed improved photocatalytic activity due to optimal anatase crystallinity and surface area.     

Crystal structure and thermal expansion of ammonium pentaborate NH<Subscript>4</Subscript>B<Subscript>5</Subscript>O<Subscript>8</Subscript>

Anhydrous ammonium pentaborate NH₄B₅O₈ has been synthesized by thermal dehydration of larderellite NH₄[B₅O₇(OH)₂] · H₂O at a temperature of 290°C for 7 h. The crystal structure has been determined from the X-ray powder diffraction data: a = 7.58667(5) Å, b = 12.00354(8) Å, c = 14.71199(8) Å, R _p = 6.23, R _wp = 7.98, R _B = 12.7, R _F = 8.95, and β-KB₅O₈ structure type. The double interpenetrating framework is formed by pentaborate groups, each consisting of a boron-oxygen tetrahedron and four triangles, in which all oxygen atoms are bridging. The thermal behavior of the NH₄B₅O₈ compound has been investigated using thermal X-ray diffraction. As for other pentaborates of this type, the thermal expansion of the NH₄B₅O₈ compound is anisotropic and reaches a maximum along the a axis. The thermal expansion coefficients are as follows: α _a = 39 × 10^?6, α _b = 6 × 10^?6, α _c = 20 × 10^?6, and α _V = 65 × 10^?6 °C^?1.     

Multi-functional Polyester Hollow Fiber Nonwoven Fabric with Using Nano Clay/Nano TiO2/Polysiloxane Composites

Surface modification and property improvement of hollow polyester fiber nonwoven fabric is very important due to the application of substrate in the various fields. Here, nano clay, nano TiO₂ and polysiloxane softener as been applied on the hollow polyester fiber nonwoven fabric through conventional impregnation-dry-cure method in order to enhance the fabric properties. The alkaline hydrolysis of polyester was performed on the nonwoven surface to functionalize the fabric and increase the nanoparticles uptake. The nano clay was first dispersed by using nonionic dispersing agent, and then nano titanium dioxide dispersion was added dropwise to the prepared nano clay dispersion. Also, other dispersions were prepared with adding polysiloxane softener and polyurethane resin under sonication. The SEM images and EDX/XRD patterns indicated the presence of various applied particles on the surface of the fabric. Thermal gravimetric analysis was employed to investigate the thermal decomposition behavior of the treated samples. Self-cleaning properties of polyester nonwoven treated by TiO₂/nano clay/polysiloxane composite was followed by degradation of methylene blue under daylight irradiation at ambient temperature. It was found that nano clay/TiO₂/polysiloxane composite on the fabric surfaces improved self-cleaning property, thermal stability above 400 °C, and water absorption properties of the fabric.     

Structural characterization and superconducting properties of MgB<Subscript>2</Subscript> prepared by SHS-method

Self-propagating high-temperature synthesis (SHS) of bulk MgB₂ superconductor from Mg-2B powder blend is reported. This reaction proceeds violently at 100 A under a protective atmosphere. Since the heat of reaction of Mg and B was not enough for chain reaction, then (Ti + C) mixed powders were used as the ignition agent to assist the reaction (Mg + 2B). In this case, the combustion front moved without any difficulty. The diffraction lines of the product can be indexed to a hexagonal MgB₂ phase, with lattice constants a = 3.0845 Å, and c = 3.5259 Å. For comparison, the direct synthesis of (Mg + 2B) mixture was carried out at (800°C–1000°C). It can be found, that high-temperature sintering (1000°C) will induce the formation of impurities. The MgB₂ grains are fine, well compacted and more homogenous. The structure of materials was studied using XRD, FESEM and EDX. M-H curvatures were measured under the magnetic fields between ?80 kOe and 80 kOe. J _c was calculated from width of magnetization hysteresis loops based on the extended Bean Model.     

Fabrication of superhydrophilic self-cleaning SiO2–TiO2 coating and its photocatalytic performance

Generally, superhydrophilic self-cleaning coatings are prepared from semiconductors with photocatalytic properties. Organic pollutants attached to the coating surface can be degraded by its photocatalytic performance realizing a self-cleaning goal. Herein, SiO₂–TiO₂ composite particles were fabricated by the hydrolysis and precipitation of TiOSO₄, and SiO₂ microspheres were chosen as carriers, which are inexpensive and environmentally friendly. Then, superhydrophilic self-cleaning SiO₂–TiO₂ coatings were fabricated by spraying the composites on the surfaces of substrates. The morphology, structure and self-cleaning performance of the SiO₂–TiO₂ coating were characterized and tested. The results revealed that nano-TiO₂ was loaded on the surfaces of SiO₂ microspheres uniformly forming a hierarchical micro/nanostructure. The SiO₂–TiO₂ composite particles exhibited excellent photocatalytic degradation performance, and the degradation rate of methyl orange (10 ppm) was more than 98% under UV irradiation for 40 min. Furthermore, the coating prepared with the SiO₂–TiO₂ composite particles exhibited superhydrophilicity. A water droplet spreads completely on the coating surface in 0.35 s, and the contact angle reaches 0°. In addition, rhodamine B (RhB) and methylene blue (MB) on the coating surface can be degraded efficiently under sunlight irradiation. The SiO₂–TiO₂ composite particles can be sprayed directly on the surfaces of concrete, brick, wood, and glass slides. Therefore, the particles showed good adaptability to different substrates. The superhydrophilic property was due to the hydrophilicity of SiO₂ and TiO₂, the hierarchical micro/nanostructure of the SiO₂–TiO₂ composites, and the photoinduced superhydrophilicity of TiO₂. The above experimental results show that the as-prepared superhydrophilic self-cleaning SiO₂–TiO₂ coating has a large application potential.     

Synthesis and Characterization of Anti-fungus,Anti-corrosion and Self-cleaning Hybrid Nanocomposite Coatings Based on Sol–Gel Process

Anti-corrosion, anti-fungus, and self-cleaning properties of coatings containing ZnO–TiO₂, SiO₂–TiO₂ and SiO₂/TiO₂/ZnO nanoparticles synthesized based on sol–gel precursors using tetra methoxysilane, 3-glycidoxypropyl trimethoxysilane, tetra (n-butyl orthotitanate) and zinc acetate dihydrate were investigated by FESEM, EDAX and TEM analyses. Results indicated uniform dispersion of inorganic nanoparticles in the range of 20–40 nm in size. Anti-corrosion property of the hybrid coating was characterized by EIS measurements and parametrically analyzed in an equivalent circuit when the coating was exposed to salt solution. Results showed that, ZnO and TiO₂ nanoparticles enhance anti-corrosion property of the hybrid coatings. Anti-fungus and anti-bacterial properties of the coatings were determined by diameter of inhibition zone and inhabitation of bacterial growth, respectively. The coating containing ZnO and TiO₂ nanoparticles showed anti-fungus and anti-bacterial properties which were related to their photocatalytic properties. Degradation of methylene blue in aqueous solution was determined by UV–Visible tests which indicated self-cleaning property of the coatings containing ZnO and TiO₂ nanoparticles.     

Density and microhardness of glasses in the SrO-B<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript> system

The density d at a temperature of 25°C is measured by the hydrostatic weighing method, the Vickers microhardness H _V is determined, and the fluctuation free volume fraction f _g is calculated for glasses in the SrO-B₂O₃-SiO₂ system with a constant strontium oxide content in the range from 35 to 45 mol %. It is demonstrated that the quantities H _V and f _g decrease and the density d increases with an increase in the SrO content.     

Effect of TiO<Subscript>2</Subscript> loading on the activity of V/TiO<Subscript>2</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> in the catalytic oxidehydrogenation of ethylbenzene with carbon dioxide

TiO₂-Al₂O₃ mixed oxides with different compositions ranging from 40wt-% to 95wt-% of TiO₂ were prepared by sol-gel method and impregnated with different amounts of VO _x . Supports and catalysts were characterized by X-ray diffraction (XRD), physisorption, temperature preprogrammed reduction (H₂-TPR), and ammonia temperature programmed desorption (NH₃-TPD). TiO₂ content in the support had obvious effect on the crystal structure, texture characteristic, acid property, and catalytic activity in dehydrogenation of ethylbenzene (EB) with carbon dioxide. The highest catalytic activity was acquired when the TiO₂ content was 50 wt-%.     

LiNi0.8Co0.15Al0.05O2 cathode materials prepared by TiO2 nanoparticle coatings on Ni0.8Co0.15Al0.05(OH)2 precursors

Synthesis, electrochemical, and structural properties of LiNi_0.8Co_0.15Al_0.05O₂ cathodes prepared by TiO₂ nanoparticles coating on a Ni_0.8Co_0.15Al_0.05(OH)₂ precursor have been investigated by the variation of coating concentration and annealing temperature. TiO₂-coated cathodes showed that Ti elements were distributed throughout the particles. Among the coated cathodes, the 0.6 wt% TiO₂-coated cathode prepared by annealing at 750 °C for 20 h exhibited the highest reversible capacity of 176 mAh g⁻¹ and capacity retention of 92% after 40 cycles at a rate of 1C (=190 mA g⁻¹). On the other hand, an uncoated cathode showed a reversible first discharge capacity of 186 mAh g⁻¹ and the same capacity retention value to the TiO₂-coated sample at a 1C rate. However, under a 1C rate cycling at 60 °C for 30 cycles, the uncoated sample showed a reversible capacity of 40 mAh g⁻¹, while a TiO₂-coated one showed 71 mAh g⁻¹. This significant improvement of the coated sample was due to the formation of a possible solid solution between TiO₂ and LiNi_0.8Co_0.15Al_0.05O₂. This effect was more evident upon annealing the charged sample while increasing the annealing temperature, and at 400 °C, the coated one showed a more suppressed formation of the NiO phase from the spinel LiNi₂O₄ phase than the uncoated sample.