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.     

Surface modification of TiO2/SiO2 composite hydrosol stabilized with polycarboxylic acid on Kroy-process wool fabric

Self-cleaning of wool fabric has been of increasing interest due to availability and practicability. In this paper, two kinds of wool fabrics, including raw wool and Kroy-process wool fabric, were successfully modified by TiO₂/SiO₂ gel stabilized by 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA), respectively. The optimum concentration of carboxylic acids and TiO₂/SiO₂ gel was decided by the crease recovery angles and total color difference (ΔE) values, respectively. The results revealed that wool fabrics treated with BTCA and TiO₂/SiO₂ had better wrinkle resistance in comparison with CA and TiO₂/SiO₂ treated samples. The decomposition of stains was studied using UV irradiation and the presence of TiO₂/SiO₂ gel demonstrated obvious self-cleaning property, in which the color of wool fabric was unchangeable. The hydrophilicity of Kroy-process wool fabric increased relative to raw ones. In addition, Scanning Electron Microscope images demonstrated the layer of TiO₂/SiO₂ nanoparticles coated on treated samples. In general, the adhesion properties coated to the fabric surface showed a slight loss even at harsh processing conditions, however, the anti-UV properties obviously increased due to the decrease in the fabric porosity. And the linkages between carboxylic acid and wool fibers were illustrated using FTIR pattern.     

A novel durable photoactive nylon fabric using electrospun nanofibers containing nanophotocatalysts

This study explores new technique to produce a nylon fabric with durable self-cleaning property. Nylon fabric (polyamide 66) has been coated with electrospun nylon nanofibers containing nanoparticles (TiO₂, SrTiO₃ and ZnO). The coated samples were heat-setted in order to fixation of the nanofibers on surface of the nylon fabric. The self-cleaning property is tested by discoloration of the stained fabric with Direct Green 6 under UV irradiation. The scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns were employed to characterize the treated nylon fabrics. The treated fabrics showed excellent photoactivity toward dye degradation. Moreover, the photoactivity of the treated fabrics stable after repeat laundering.     

Functionalization of cotton fabric with nanosized TiO<Subscript>2</Subscript> coating for self-cleaning and antibacterial property enhancement

In this study, titanium dioxide (TiO₂) was used as coating compound to add self-cleaning and antibacterial functionality properties to the cotton fabric. TiO₂-consisting coating compounds were prepared at four different processing temperatures (20, 40, 60, and 80°C) in order to examine the influence of process temperature on average particle size. Among the prepared solutions, the one prepared at 80°C process temperature was selected for the dip coating application of the 100% cotton fabric, which formed a transparent nanosized TiO₂ film on the fibrous structure of fabric. Dip coating trials were done at five coating temperatures of 20, 40, 60, 80, and 100°C. TiO₂-coated and uncoated fabric samples were then tested to evaluate their self-cleaning and antibacterial activities. A self-cleaning activity test was conducted using uncoated and TiO₂-coated fabric samples which were stained with hot tea solution via dipping method. Stained fabric samples were illuminated under a solar simulator for the color changes to measure photocatalytic degradation of stain colors. Antibacterial performance of TiO₂-coated and uncoated fabric samples was determined against pure cultures of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213.     

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.     

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.     

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.     

Investigating the role of surface treated titanium dioxide nanoparticles on self-cleaning behavior of an acrylic facade coating

In this study, the addition of silane treated TiO₂ nanoparticles on the self-cleaning properties of an acrylic facade coating was evaluated. Tetraethoxyorthosilicate, TEOS, was used for surface treatment of TiO₂ nanoparticles. The silica grafting on the TiO₂ nanoparticles was characterized via Fourier Transform Infrared spectroscopy, specific surface area measurement, pore size distribution, and real density measurements. The effect of surface treatment and content of nanoparticles on the photocatalytic activity of acrylic coating and self-cleaning properties was studied. For this purpose, the photodegradation of Rhodamine B (Rh.B) dyestuff, as a colorant model, was investigated by colorimetric technique, while the coating samples were exposed to UVA irradiation. Performance of the acrylic coating films was evaluated by gloss change during accelerated weathering conditions. Also, the surface morphology of the coating films was studied using SEM analysis. The results showed that the addition of both treated and untreated TiO₂ nanoparticles provides self-cleaning property to the acrylic coatings. However, silica surface treatment of TiO₂ nanoparticles reduces the coating degradation caused by TiO₂. This is more evident when higher concentrations of the treated TiO₂ nanoparticles are used.     

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.     

Molybdenum doped TiO2 nanocomposite coatings: Visible light driven photocatalytic self-cleaning of mineral substrates

The molybdenum doped TiO₂ nanocomposite layer double hydroxide (LDH) suspensions, Mo:TiO₂-LDHs, were synthesized by a wet impregnation method in order to enhance the pure TiO₂ (water suspension) photocatalytic activity and consequently its self-cleaning efficiency under exposure to visible light. The aim was to produce nanocomposites by a simple, energy saving and cost beneficial synthesis. The mass ratio Mo/Ti was systematically varied (0.03, 0.06, 0.09, 0.12). The obtained nanocomposite Mo:TiO₂-LDH suspensions were first characterized by UV–vis spectroscopy (band-gap energies), Zeta-sizer (particle size distribution and stability) and X-ray diffraction (XRD) (structure) and then applied onto the model mineral substrates, brick and stone. The photocatalytic activity of the obtained coating was determined based on the degradation kinetics of the Rhodamine B (RhB) under artificial visible light irradiation (white LED). The obtained results were compared to the ones of the unmodified TiO₂-LDH suspension. The obtained results also showed that all prepared nanocomposites have good photocatalytic activity, particularly the suspension Mo:TiO₂-LDH with the Mo/Ti 0.03 mass ratio which possesses the best value. In addition, as regards the visible light driven self-cleaning effect, this suspension has proven to be a good protective functional coating for porous mineral substrates (bricks and stones).     

Ga-doped ZnO transparent electrodes with TiO<Subscript>2</Subscript> blocking layer/nanoparticles for dye-sensitized solar cells

Ga-doped ZnO [GZO] thin films were employed for the transparent electrodes in dye-sensitized solar cells [DSSCs]. The electrical property of the deposited GZO films was as good as that of commercially used fluorine-doped tin oxide [FTO]. In order to protect the GZO and enhance the photovoltaic properties, a TiO₂ blocking layer was deposited on the GZO surface. Then, TiO₂ nanoparticles were coated on the blocking layer, and dye was attached for the fabrication of DSSCs. The fabricated DSSCs with the GZO/TiO₂ glasses showed an enhanced conversion efficiency of 4.02% compared to the devices with the normal GZO glasses (3.36%). Furthermore, they showed better characteristics even than those using the FTO glasses, which can be attributed to the reduced charge recombination and series resistance.     

Experimental study on the treatment of volatile organic compound vapors using a photoreactor equipped with photocatalyst‐coated fabrics

In this study, methods were developed to enlarge the scope of traditional applications of titanium dioxide (TiO₂) and to increase the value of felted fabric by allowing volatile organic compound (VOC) degradation as well as dust filtration in a photoreacting fabric filter. In the past, when a V–Ti mixed catalyst was used, the application of felted fabric as a support material for the catalyst was difficult because the active temperature of the catalyst ranged from 250 to 400°C. Thus, in this study catalyst‐coated felted fabric was manufactured at normal temperature conditions, and then fundamental de‐VOC performance tests were conducted under irradiation condition to develop a fabric filter having a de‐VOC function in addition to a dust‐filtration function. Toluene vapor was selected as a sample VOC because it poses health hazards, has been widely used as an organic solvent, and has been known as a compound that is difficult to dissociate. To manufacture and use a fabric filter that degrades VOC_S, and removes dust particles through using photocatalyst‐coated fabrics and light sources, optimum operating conditions were obtained by observing the degradation attributed to varying the toluene‐vapor flow rate, the initial toluene concentration, flue gas humidity, TiO₂ loading onto the surface of the fabric, and the intensity and wavelength of a near ultraviolet light lamp. To keep the flue gas humidity at a relatively constant level, a system to automatically control the humidity was constructed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3174–3179, 2004     

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.     

Preparation of highly stable superhydrophobic TiO2 surfaces with completely suppressed photocatalytic activity

TiO₂ nanoparticles with a mean size of 20–30 nm were covered by ultrathin polydimethylsiloxane (PDMS) film, which shows hydrophobic properties. Surfaces consisting of the PDMS-coated TiO₂ particles showed water contact angles close to 170°. In contrast to the hydrophobic films consisting of organic molecules, which can be photocatalytically decomposed on TiO₂ in the presence of UV light, PDMS-coating on TiO₂ was highly stable. The PDMS-coating completely suppressed the photocatalytic activity of TiO₂. The unique properties of PDMS-coating can be exploited for UV protection layer and self-cleaning surfaces.     

Microstructure and electric properties of (Na0.85K0.15)0.5Bi0.5TiO3 composited films with alternative TiO2 layers

In this work, in order to investigate the effect of TiO₂ layer on the microstructure and piezoelectric properties of (Na_0.85K_0.15)_0.5Bi_0.5TiO₃ (NKBT) thin films, TiO₂ layer was inserted at the interface between the NKBT thin film and substrate and on both sides of the NKBT, i.e., at the interface and on the top of the NKBT thin film. NKBT composited films with alternative TiO₂ layer were deposited on Pt/Ti/SiO₂/Si substrate by aqueous sol‐gel method. X‐ray diffraction observation found that the degree of (100) preferred orientation strengthened with TiO₂ layers added, especially on both sides of NKBT thin film. The TiO₂/NKBT/TiO₂ composited film with both TiO₂ layer of 40 nm thickness exhibited a remnant polarization value P_r of 22.6 μc/cm³ and effective piezoelectric coefficient of approximate 77 pm/V, which are much larger than that of the single‐layered NKBT thin film with P_r value of 13.7 μc/cm³ and of 56 pm/V, respectively. According to the investigation of the temperature‐dependent ferroelectric property, it was found that the P_r gradually increased, and in the meantime the coercive voltage gradually moved to higher voltage with testing temperature varied from 20 to ?150°C. Besides, applied voltage dependence of leakage current density measurement indicated that the TiO₂ layer would effectively lower the leakage current of the films, and the TiO₂/NKBT/TiO₂ composited film both TiO₂ layer of 40 nm exhibited the lowest leakage current.     

Large enhancements in hydrogen production of TiO2 through a simple carbon decoration

A simple carbon decoration, involving only immersion in adipic acid followed by calcination in N₂ atmosphere, was developed to prepare thin carbon layer decorated TiO₂ nanoparticles. The thin carbon layer was in tight contact with the TiO₂ domain and served as an electron trapping center to improve charge separations necessary for enhancement in photocatalytic water splitting performance of the TiO₂ nanoparticles. With an optimal carbon loading of 0.3 wt%, a fourfold improvement was achieved for hydrogen production as compared with that achieved by pristine TiO₂ nanoparticles. This simple carbon decoration provides a promising low-cost alternative to traditional Pt-decoration approaches for enhancing hydrogen productions from photocatalytic water splitting.     

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.     

Tailoring Unidirectional Water-Penetration Janus Fabric with Surface Electrospun Deposition

This paper provides a new method to fabricate an integrated Janus fabric that has excellent unidirectional water-penetration property. Based on commercial polyester fabric that is pretreated with CaCl₂ solution, polyvinyl alcohol/sodium alginate (PVA/SA) solution is deposited directly on the fabric via electrospinning and in situ chelated with Ca²⁺ contained in the fabric. The in situ formed PVA/SA gel coating not only transfers the surface of polyester fabric from hydrophobic to hydrophilic but also retains original porous structure of polyester fabric. As the water droplet contacts with unelectrospun side of modified polyester fabric (M-PET) pretreated with 10 wt% CaCl₂, it penetrates through the M-PET within 1 s from unelectrospun side to electrospun side after application, and disappears on unelectrospun side within 2 s, and in turn, droplet spreads out on electrospun side of M-PET within 2 s after application and no penetration occurs. The M-PET pretreated with CaCl₂ solution has outstanding antistatic property, vapor, and air permeability. The impact of ratio (v/v) of the PVA and SA solution and the concentration of CaCl₂ pretreating solution on properties of the M-PET are investigated.     

TPD study of the reaction of CH3CH2SH and (CH3CH2)2S2 on ZnO(0001) and ZnO

Superior activation of on 1 wt% Pt/TiO₂ catalysts for the oxidation of CO was attained by loading a large amount of Fe-oxide (100 wt%) and TiO₂. In situ IR spectra of CO proved that the structural transformation is brought about on the Pt-sites by loading of Fe-oxide, where predominant Pt-sites giving linear CO change to highly reactive bridge CO Pt-sites. In contrast, no transformation of the linear CO sites to the bridge CO sites takes place by loading of TiO₂ but the environment of Pt-sites for linear CO is changed.     

Preparation of high solids content nano-titania suspensions to obtain spray-dried nanostructured powders for atmospheric plasma spraying

Nanosized TiO₂ powder with an average primary size of ∼20 nm and surface area of ∼50 m²/g (Aeroxide^® P25, Degussa-Evonik, Germany) was used as starting material. A colloidal titania suspension from the same supplier was also used (W740X). The dispersing conditions were studied as a function of pH, dispersant content, and solids loading. Well-dispersed TiO₂ nanosuspensions with solids contents up to 30 vol.% (62 wt%) were obtained by dispersing the powder with 4 wt% PAA. Suspensions with solids contents as high as 35 vol.% were prepared by adding the TiO₂ nanoparticles to the TiO₂ colloidal suspension under optimised dispersing conditions.TiO₂ powder reconstitution was performed by spray drying both types of nanosuspensions to obtain free-flowing micrometre-sized nanostructured granules. The spray-dried nanostructured TiO₂ granules were deposited on austenitic stainless steel coupons using atmospheric plasma spraying. Coating microstructure and phase composition were characterised using scanning electron microscopy and X-ray diffraction techniques.