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Gas sensor based on point contact tungsten trioxide (WO3) was prepared by in-situ induction-heating thermal oxidation of tungsten filaments. X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM) were employed to analyze the phase and the morphology of the fabricated thin films. The results showed that the WO3 films exhibited a monoclinic phase and were composed of hierarchical micro and nano crystals. The NO2 (1-8 ppm) sensing properties of the point contact sensors based on Pure and Au-sputtering doped (2.5 at%) WO3 films were investigated. The results showed that the gas sensing properties of the Au (2.5 at%) doped WO3 sensors were superior to those of the undoped. The obtained point contact WO3 sensor exhibited the maximum NO2 gas response at 100°C.

In order to improve the visible light response in titania photocatalysts, CuO/TiO2 heterojunction nanostructures (CuO-TNT) were proposed and fabricated via the electrochemical process. TiO2 nanotubes array (TNT) was first fabricated by secondary anodization, after that the CuO was doped by the electrodeposition. The thin film was characterized by X-ray diffraction (XRD), diffuse reflection spectra (DRS) and field emission scanning electron microscopy (FESEM). Besides, its photoelectrochemical properties were measured in 0.1 M Na2SO3 solution. By comparing the results under different conditions of deposition, it was found that the deposition current density was a crucial parameter for controlling the morphology and the photoelectrochemical properties of the samples.

Smooth and aligned TiO2-WO3 composite nanotube arrays (TiW-NTA) were successfully fabricated on a Ti-W alloy via an anodization process. The crystal phase and surface morphology of the nanostructured film were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The photoelectrochemical properties of the as-prepared samples were studied by measurement of the photocurrent response and open-circuit potential. The TiO2-WO3 nanotube arrays were found to be capable of a more than 2.5h discharge relaxation due to its energy storage behavior.

Crystalline anatase TiO2 thin films were obtained on glass substrates at 60°C, 75°C and 90°C, respectively, by liquid phase deposition (LPD) method without subsequent heat treatment. X-ray diffraction (XRD), atomic force microscopy (AFM) and UV-Vis spectrophotometer were used to characterize the as-synthesized TiO2 thin films. The H2 sensing properties of the TiO2 thin films based sensors were investigated. The results show that the gas sensors signal Ra/Rg (Ra: resistance in air, Rg: resistance in a sample gas) decreases with the increasing deposition temperature. The TiO2 thin films obtained at deposition temperature of 60°C exhibited the maximum H2 gas response at 350°C, and the magnitude of the sensor signal and the response time for 500ppm H2 was 1.25 and 17s, respectively.

A dye-sensitized TiO2 nanotube array (DST) was fabricated by electrochemical anodization in an aqueous organic electrolyte and immersed into ethanol containing N719 dye. The crystal phase and microstructure of the TiO2 nanotube array (TNTA) were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The UV-Vis spectra of the DST were characterized by diffuse reflectance spectra (DRS). The hydrogen sensitivity of the as-prepared sample was tested at room temperature under Xe-lamp (simulated solar light) irradiation. It was found that the sensor was highly sensitive to low concentrations of hydrogen as an application in air quality control.

To improve its visible light response capability, a new narrow bandgap zinc ferrite semiconductor was in-situ introduced into the matrix of titanium dioxide nano film. ZnFe2O4 doped TiO2 composite films have been successfully formed on glass and stainless steel substrates from aqueous solution through equilibrium reaction between iron (III)-titanium (IV)-fluoric complex and boric acid, followed by in-situ hydrothermal conversion and crystallization in the Zn2+-contained basic environment. The obtained films were densely packed and had no visible cracks; clear photovoltaic responses were observed in the anodic direction, and they were much larger in the presence of ferrite dopant. It is suggested that the shift of the corrosion potential was ascribed to photo-induced charge separation between the conduction band of ZnFe2O4 and its counterpart TiO2 nano-particles.

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TiO2 is one kind of semiconductor-based photocatalyst. TiO2 shows relatively high reactivity and chemical stability under ultraviolet (UV) light. However TiO2 is a poor absorber of photons in visible light. In order to improve the absorption efficiency, the coatings of TiO2/WO3, WO3 and TiO2 on ITO were prepared by liquid phase deposition (LPD) and dip coating method, their microstructure, surface properties, photoelectrochemical properties are investigated in this paper. XRD results showed that the phases on the composite coatings are mainly anatase, rutile and WO3 respectively, the SEM results showed that the coatings of TiO2 and TiO2/WO3 are distributed evenly on the materials surface. The electrochemical experiment results showed that open circuit potential of TiO2 and TiO2/WO3 with presence of the UV light illumination were about -343 mV and –650 mV respectively, comparatively the rest potential of 304 stainless steel is about 48 mV, which means that the TiO2 or TiO2/WO3 coatings can protect 304 stainless steel from corrosion, and TiO2/WO3 coatings retained for a while anticorrosion even absence of UV light.

TiO2 is one kind of semiconductor-based photocatalyst. TiO2 shows relatively high reactivity and chemical stability under ultraviolet (UV) light. However TiO2 is poor absorber of photons in the solar spectrum. In order to improve the absorption efficiency, the coatings of TiO2/ZnFe2O4, ZnFe2O4and TiO2 on ITO were prepared by dip coating method, their microstructure, surface properties, photocurrent and photo absorption are investigated in this paper. XRD results show that the phases on the composite coatings are mainly TiO2 and ZnFe2O4 and the main phase on ZnFe2O4 and TiO2 coatings is ZnFe2O4 and TiO2 respectively, the SEM results show that the coatings of TiO2 and TiO2/ZnFe2O4 are distributed evenly on the materials surface and the AFM results show that the grain size is about 20nm. The experimental results also show that the absorption wavelength of composite coatings of TiO2/ZnFe2O4 is 454nm, which is larger than that of TiO2 coatings (370nm). Under the irradiation of Xe lamp light, a photocurrent of 27µA/cm2 on the materials surface could be obtained.

N-doped TiO2 nanostructured composite (TiO2-N) films with excellent photocatalytic performance under visible light were successfully formed on glass and stainless steel substrates by spin-coating process. The photoreduction performance of as-prepared coatings was characterization by reduction of Ag+ and measurement of photovoltaic response. It was found that Ag+ can be easily reduced to metallic Ag and obvious photocurrent and photovoltage were observed by V-I recording under visible light irradiation. Crystalline structure, nitrogen states in the lattice, composition and surface morphology of the nanostructured films were analyzed by XRD, XPS and SEM.

Anodic aluminum oxide (AAO) is commonly used as a starting template for fabrication of several kinds of functional nanoscale devices due to its homogeneous nanohole structure with high aspect ratio. In this paper, high density and uniform titanium dioxide nanotube array films were prepared via liquid phase deposition method by immersing the AAO templates in an aqueous ammonium hexafluorotitanate solution. The phase and microstructure of the nanotube array films were characterized by X-ray diffraction and field-emission scanning electron microscopy. It was found that the mean inner diameters of nanotube are 40-100 nm, mainly depended on different templates and post treatment condition; the phase of as-deposited TiO2 array film was amorphous, while it became anatase at above 400°C.