Preparation and characterization of ternary composite films of polyvinyl alcohol/sodium alginate/TiO<Subscript>2</Subscript>

Nano-TiO₂ with anionic surface active agent sodium dodecylsulfate (SDS) modified, the poly(vinyl alcohol)/sodium alginate/TiO₂ composite films were prepared by method of solution blending representing. The structure of the films was analyzed by XRD and SEM. In addition, air permeability rate, swelling ratio, light transmittance, mechanical properties, and antibacterial properties were tested. The results showed that in compound membrane there was a strong force between poly(vinyl alcohol)/sodium alginate and TiO₂ particles, indicating that there was good compatibility between the sodium alginate and the poly(vinyl alcohol). The mixed membranes were of good water resistance, tensile strength, and closure. When the titanium dioxide content increased appropriately, they had very good mechanical properties. In addition, the antibacterial properties of composite membrane gradually increased with the increase in the TiO₂content.     

Preparation and photoelectrochemical performance of TiO<Subscript>2</Subscript>/Ag<Subscript>2</Subscript>Se interface composite film

Coupling TiO₂ with a narrow band gap semiconductor acting as the photosensitizer has attracted much attention in solar energy exploitation. In this work, the porous TiO₂ film was first formed on the conducting glass plate (CGP) substrate by the decomposition of polyethylene glycol (PEG) mixing in titanium hydroxide sol at 450°C. Then, the TiO₂/Ag²Se interface composite film was fabricated by interface reaction of AgNO₃ with NaSeSO₃ on the activated surface of porous TiO₂ film. The results of SEM and XRD analyses indicated that the porous TiO₂ layer was made up of the anatase crystal, and the Ag₂Se layer was made up of congregative small particles that have low-temperature α-phase structure. Due to its efficient charge separation for the photo-induced electron-hole pairs, the TiO₂/Ag₂Se interface composite film as-prepared has good photovoltaic property and high photocurrent response for visible light, which have been confirmed by the photoelectrochemical measurements.     

TiO<Subscript>2</Subscript> nanofibers embedding single crystalline TiO<Subscript>2</Subscript> nanowires

Epitaxially grown titanium dioxide (TiO₂) nanofibers embedding single crystalline TiO₂ nanowires (NWs) were successfully fabricated by electropinning poly(vinyl pyrrolidone)/ethanol solutions mixed with hydrothermally synthesized TiO₂ NWs and titanium isopropoxide precursors and subsequently calcinating the electrospun nanofibers. Utilizing scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the morphologies of TiO₂ NWs and nanofibers were investigated. High resolution TEM (HR-TEM) and selected area electron diffraction (SAED) allowed us to indentify the fact that, during the calcination process under the optimized condition, titanium isopropoxide precursors were epitaxially crystallized on the surface of single crystalline TiO₂ NWs. Based on the X-ray diffraction (XRD) experiments, it was also realized that the crystalline structure of hydrothermally synthesized TiO₂ NWs and epitaxially crystallized TiO₂ nanofibers is anatase and that TiO₂ composite nanofibers embedding TiO₂ NWs exhibited a higher crystallinity than the pristine TiO₂ nanofibers. Additionally, ultraviolet visible (UV–Vis) spectra of nanofibers indicated that optical properties of TiO₂ nanofibers can be tuned by introducing the single crystalline TiO₂ NWs.     

Synthesis and characterization of a new hybrid TiO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> filler for lithium conducting gel electrolytes

This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes. Hybrid TiO₂-SiO₂ ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion batteries based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF/HFP) copolymeric membranes. The powders, dry membranes and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte uptake and electrochemical characteristics in Li-ion cells.     

Fabrication and characterization of TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> composite nanoparticles and polyurethane/(TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript>) nanocomposite films

TiO₂–SiO₂ composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO₂–SiO₂ composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO₂–SiO₂) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO₂–SiO₂ composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO₂–SiO₂ composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO₂–SiO₂ core surface via surface functionalized reaction. The particle size of TiO₂–SiO₂ composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid films. The average particle size of the TiO₂–SiO₂ composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO₂–SiO₂ composite nanoparticles are well dispersed in the PU matrix.     

Photodegradation of orange II dye using p-n junction NiO/TiO2 composite,and assessment of its biological activities

The chemical reduction method was used to synthesize nickel oxide particles (NiO) and NiO supported on titanium dioxide (NiO/TiO₂ nanocomposite). The composites were characterized through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The morphological investigation showed that pseudocubic NiO are present in dispersed as well as agglomerated forms. Whereas NiO particles (<200 nm) are evenly deposited over the surface of TiO₂ in NiO/TiO₂ composite. The formation of NiO and NiO/TiO₂ was also verified by XRD analysis. The synthesized NiO and NiO/TiO₂ were used as photocatalysts for the degradation of Orange II (OII) dye. According to the degradation investigation, both NiO and NiO/TiO₂ composite degraded OII dye more efficiently when exposed to UV light. The results indicated that NiO degraded 93% and NiO/TiO₂ composites degraded approximately 96% of OII dye within 30 min. Both photocatalysts are highly sustainable and have significant OII dye degradation recyclability. Moreover, NiO and NiO/TiO₂ exhibited promising bioactivities (antioxidant activity of 80%) against the pathogenic bacteria Citrobacter and Providencia, which is comparable with the standard ascorbic acid (88%).     

Preparation of TeOx–SiO2 film with excellent third-order nonlinear optical properties by electrochemically induced sol–gel method

TeO_x-SiO₂ composite films having third-order nonlinearities were prepared by electrochemically induced sol-gel deposition method on ITO substrate.The third-order optical nonlinearities of the films were measured by Z-scan technique.The third-order nonlinear susceptibilities(χ^（3）) of the as-prepared films are 5.9×10^-7 to 4.29×10^-6esu.The surface morphology and composition of the films were characterized by SEM/EDX,which identified that Te metallic particles well dispersed in TeO_x-SiO₂ gel films.     

Evaluation of the structural,optical and photocatalytic properties of nitrogen-fluorine co-doped TiO<Subscript>2</Subscript> thin films

Nanostructured TiO₂ films were synthesized by a modified sol–gel method using Pluronics P-123 (EO₂₀PO₇₀EO₂₀) as templating agent, titanium n-butoxide [Ti(OC₄H₉)₄] as inorganic precursor, and ammonium fluoride (NH₄F) as the source of N and F dopant atoms in order to prepare sols of x(NF) TiO₂ (x=2, 5, 10, 20 wt%). The thin film preparation was made by spin coating, followed by calcination at 400 °C. The as-prepared TiO₂ and xNF-TiO₂ films were characterized by XRD, Raman spectroscopy, FTIR, TGA-DTA, SEM, UV–Vis diffuse reflectance spectroscopy and EPR. XRD and Raman spectroscopy show that the crystalline structure of these samples consists exclusively of the anatase phase. The band gap (E _g ) values for the doped 10 and 20 NF-TiO₂ film systems were found to be significantly smaller than those corresponding to the rest of the other TiO₂ films. The photocatalytic properties of these films are investigated by following the degradation of methyl orange in aqueous solution under UV irradiation. The photodecomposition is mainly a direct function of the amount of NF present in the TiO₂ matrix. The 20NF-TiO₂ sample shows the highest activity of all the samples studied.     

Studies on UV‐stability of poly(MMA‐co‐M12‐co‐BPMA)/TiO2composite particles prepared by ultrasonically initiated emulsion polymerization

In this paper, poly(methyl methacrylate‐co‐sodium sulfopropyl lauryl maleate‐co‐2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylpropoxy) benzophenone)/TiO₂ (i.e., poly(MMA‐co‐M12‐co‐BPMA)/TiO₂) composite particles were prepared by ultrasonically initiated emulsion polymerization. To study the dispersion and UV‐stability of the composite particles, laser diffraction particle size analyzer (LDPSA), ultraviolet‐visible absorption spectroscopy (UV‐vis), UV‐vis diffuse reflectance spectroscopy (DRS), differential scanning calorimeter (DSC), and the weight loss measurement were used. The results indicate that the dispersion of the poly(MMA‐co‐M12‐co‐BPMA)/TiO₂ composite particles prepared by ultrasonically initiated emulsion polymerization is good. And the composite particles can absorb UV light; the ultraviolet absorption strength of poly(MMA‐co‐M12‐co‐BPMA) grafted onto the surface of TiO₂ has not changed after UV irradiation while that of PMMA changed significantly. The UV absorption strength, weight loss, and Tg changes are in the order PMMA> poly(MMA‐co‐M12‐co‐BPMA) >PMMA grafted onto TiO₂> poly(MMA‐co‐M12‐co‐BPMA) grafted onto TiO₂. These results show that the ultrasonically initiated emulsion polymerization will enhance the UV stability of composite particles, and the UV‐stability of PMMA can be enhanced by the introduction of the organic UV‐stabilizer BPMA and the inorganic UV‐stabilizer titanium dioxide into the PMMA chains by covalent bond, and the effect of the BPMA and the TiO₂ used together is better than that used, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

One‐Pot Synthesis of Nitrogen‐doped TiO2 Nanowires with Enhanced Photocurrent Generation

A nitrogen‐doped TiO₂ (N‐TiO₂) nanowire film was synthesized via a one‐pot hydrothermal method using triethylamine as nitrogen source. The effect of the concentration of the triethylamine on the films was evaluated. In addition, the N‐TiO₂ nanowires were characterized using field‐emission scanning electron microscopy (FE‐SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and ultraviolet–visible spectroscopy. A 3.2× enhancement of the photocurrent for N‐TiO₂ (0.6) was achieved over the as‐prepared TiO₂ nanowire, under AM1.5G solar illumination. This was due to nitrogen doping, which could narrow the bandgap of titania to extend the adsorption of the catalyst to the visible light region.     

Comparison of the photonic effects of Mn-CNT/TiO<Subscript>2</Subscript> composites modified by different oxidants

Manganese-carbon nanotubes (CNTs) on titania (TiO₂) composites modified by different oxidants (KMnO₄, (NH₄)₂S₂O₈ and m-chlorperbenzoic acid (MCPBA)) were prepared with a sol-gel method. These composites were comprehensively characterized by the Brunauer-Emett-Teller (BET) method, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy EDX, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis absorption spectroscopy. The photoactivity of these materials prepared under visible light irradiation was tested using methylene blue in aqueous solution. The result shown that among the three oxidants, the MCPBA was the best one for the surface functionalization of CNTs and the manganese treated CNT/TiO₂ composite can enhance the photocatalytic activity. The proposed mechanism of the photodegradation of methylene blue on Mn-CNT/TiO₂ composites was present.     

Surface modification of NiCdO barrier layer in complex photoanodes and TiO<Subscript>2</Subscript> protective coating for efficient and stabile water dissociation

This work presents a follow-up research of our previously published work. Herein, the photocatalytic performance of a nanostructured CdZnO/NiCdO composite photoanode has been improved by intercalation of Cu catalyst atoms in the electron barrier layer of Ni_yCd_1?yO surface by an ion exchange process. As a result, the photocurrent yield increased by 29 % at +1 V potential against Ag/AgCl. This phenomenon was tentatively attributed to the increased electron concentration and/or interaction of the Cu3d electrons with the mid-energy valence electrons. To the contrary, the introduction of Ag, Co, and Ni deteriorated the photocatalytic performance. The corrosion challenges were assessed during 50 cycles of voltammetry. The background of the degradation/photocorrosion was studied with SEM, EDX, and XPS analysis. To combat the photocorrosion, the photoanodes were coated with TiO₂ protective nanolayers of different thickness. The results for the photocurrent stability at a constant potential of +1 V showed that 9 nm TiO₂ coating improved the durability of the photoanode on account of a photocurrent decrease for about 50 %. XPS studies proved that the degradation/corrosion changes on the photoanode’s surface could be associated with an irreversible electrochemical oxidation of CdO into CdO₂.     

Electrospinning fabrication of mesoporous nano Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-TiO<Subscript>2</Subscript>@activated carbon fiber membrane for hybrid removal of phenol from waste water

A mesoporous iron–titanium mixed-oxides@activated carbon(AC) fiber membrane was fabricated by an electrospinning method and applied to the treatment of phenol waste water. The physical and chemical properties of the composite fiber membrane were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption, UV–Vis light diffuse reflectance spectroscopy (DRS), Raman spectroscopy, respectively. The results indicate that the composite nanofiber membrane is composed of α-Fe₂O₃, anatase TiO₂ and activated carbon phases with a specific surface area of 231 m² g^–1 and narrow pore size distribution of 3–6 nm. DRS reveals that the composite membrane has high photons absorption from both ultraviolet light and visible light irradiation owing to the combination of Fe₂O₃, TiO₂ and carbon. The prepared nano Fe₂O₃–TiO₂@AC fiber membrane can act as an efficient reusable photocatalyst and adsorbent for 100% remo val of phenol pollutant. This hybrid technique is hopeful to be widely used in the treatment of various organic waste waters.     

Titania nanocomposite films derived by modified sol-gel process for photovoltaic application

Titania nanocomposite films were fabricated by spin-coating from sol-gel derived pastes of TiO₂ powder in titanium isopropoxide sol. The thin films were characterized for structural, optical and hydrophilic properties and evaluated as electrodes in a photoelectrochemical cell. Addition of TiO₂ powder increased film thickness, reduced transmittance, water contact angle and electrochemical impedance, and promoted photocurrent generation. Increasing Triton X-100 surfactant loading in the composite slurry influenced film texture and transmittance, and the resultant films exhibited a lower photocurrent yield but were more hydrophilic to favor charge transfer at the electrode/electrolyte interface. The aggregation of TiO₂ particles of different sizes in the composite film facilitates light-scattering and electron transport to enhance quantum efficiency. The addition of Triton X-100 surfactant influences the distribution of scattering centers to increase transparency.     

Nanosized TiO<Subscript>2</Subscript> particles decorated on SiO<Subscript>2</Subscript> spheres (TiO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript>): synthesis and photocatalytic activities

Nanosized TiO₂ and nano-anatase TiO₂ decorated on SiO₂ spherical core shells were synthesized by using a sol–gel method. The synthesized pure TiO₂ nano particle and TiO₂ grafted on SiO₂ sphere with various ratios have been characterized for their structure and morphologies by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrophotometry (FTIR) and transmission electron microscopy (TEM). Their surface areas were measured using the BET method. The photocatalytic activity of all nanocomposites was investigated using methylene blue as a model pollutant. The synthesized TiO₂/SiO₂ particles appeared to be more efficient in the degradation of methylene blue pollutant, as compared to pure TiO₂ particles.     

Uniformly Dispersed and Controllable Ligand‐Free Silver‐Nanoparticle‐Decorated TiO2 Nanotube Arrays with Enhanced Photoelectrochemical Behaviors

Homogeneously dispersed silver nanoparticles (AgNPs) were successfully decorated onto the surface of TiO₂ nanotube arrays (TNTA) by means of an in situ photoreduction method. TNTA films as supports exhibit excellent properties to prevent agglomeration of AgNPs, and they also avoid using polymer ligands, which is deleterious to enhancing the properties of the fabricated NPs. The silver particle size and its content could be controlled just by changing the immersion time. Detailed SEM and TEM analyses combined with energy‐dispersive X‐ray spectroscopy analyses with different immersion times (5, 10, 30, 60 min) have revealed the variation tendency. The prepared Ag/TNTA composite films were also characterized by XRD, X‐ray photoelectron spectroscopy, and high‐resolution TEM. The UV/Vis diffuse reflectance spectra displayed a redshift of the absorption peak with the growth of AgNPs. The photocurrent response and the photoelectrocatalytic degradation of methyl orange (MO) were used to evaluate the photoelectrochemical properties of the fabricated samples. The results showed that the photocurrent response and photoelectrocatalytic activity largely depended on the loaded Ag particle size and content. TNTA films with a diameter of 17.92 nm and silver content of 1.15 at % showed the highest photocurrent response and degradation rate of MO. The enhanced properties could be attributed to the synergistic effect between AgNPs and TiO₂. To make good use of this effect, particle size and silver content should be well controlled to develop the electron charge and discharge process during the photoelectrical process. Neither smaller nor larger AgNPs caused decreased photoelectrical properties.     

Preparation,characterization, and thermal studies of γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> and CuO dispersed polycarbonate nanocomposites

Polycarbonate with γ-Fe₂O₃ and CuO dispersions were carried out by solvent casting method to make polycarbonate-γ-Fe₂O₃ and polycarbonate-CuO composite films. These films were characterized for the molecular structure through FTIR spectroscopy and crystallinity by X-ray diffraction (XRD) measurements. The morphology of polycarbonate-γ-Fe₂O₃ was found to be different from that of polycarbonate-CuO composite films based on the scanning electron micrograph (SEM) images. The thermal traces of composites are different from that of pure polycarbonate which indicating the catalytic decomposition when compared with virgin polymer which is oxidative decomposition. An understanding of the structure, morphology, and thermal behaviour of the composite films are envisaged in the present study.     

Electrochemical preparation of PMeT/TiO<Subscript>2</Subscript> nanocomposite electrochromic electrodes with enhanced long-term stability

In this work, 3-methylthiophene (MeT) was electrochemically incorporated with nano- and mesoporous TiO₂ films to form poly(3-methylthiophene) (PMeT)/TiO₂ nanocomposite electrochromic electrodes. TiO₂ films, which were previously coated on the ITO glass sheets through a well-established technique, were introduced to enhance the adhesion of the polymers to the substrates and thus increase the long-term stability of the devices. With this effort, the nanocomposite electrodes were found to retain up to 60% of their optical response after 3,500 deep and double potential steps and retain up to 50% of their electroactivity after 10⁴ same steps, exhibiting enhanced long-term stability. Switching time and the maximum optical contrast (ΔT%) of the nanocomposite electrodes were found to be 0.6 s and 45%, respectively. Moreover, our work showed that electrochemically incorporating conductive polymers (CPs) with TiO₂ mesoporous films was an effective method to form high-quality CP/TiO₂ nanocomposite electrodes, which can be used widely in battery cathodes, photovoltaic cells, photocatalytic reaction, and photoelectrochromic cells and were supposed to enhance their performances.     

Controllable incorporation of CdS nanoparticles into TiO<Subscript>2</Subscript> nanotubes for highly enhancing the photocatalytic response to visible light

A constant current electrochemical deposition was employed to incorporate CdS nanoparticles into the TiO₂ nanotube arrays (TiO₂NTs). The size and amount of CdS nanoparticles in TiO₂NTs (CdS@TiO₂NTs) were controllable via modulating current, deposition time and electrolyte concentration. It was revealed, from the scanning electron microscopy (SEM) images and X-ray photoelectron spectroscopy (XPS) in depth profile, that CdS nanoparticles were filled into TiO₂ nanotubes. A shift of the absorption edge toward the visible region under the optimal electrodeposition condition was observed with the diffuse reflectance spectroscopy (DRS). A 5-fold enhancement in the photocurrent spectrum for TiO₂NTs was observed and the photocurrent response range was significantly extended into the visible region because of the CdS incorporation. Compared with pure TiO₂NTs, under a visible light irradiation, CdS@TiO₂NTs exhibited a 3.5-fold improvement of photocatalytic activity, which was demonstrated by the photocatalytic decomposition of Rhodamine B (RhB).     

PbO<Subscript>2</Subscript>-TiO<Subscript>2</Subscript> composites: Electrosynthesis and physicochemical properties

Fundamental aspects of electro deposition of PbO₂-based composites containing titanium dioxide particles were studied. The content of the dispersed phase in the composite depends on the electrolyte composition and deposition conditions. Incorporation of titanium dioxide particles into PbO₂ leads to significant changes in the morphology and structure of the deposit.