Papers by Author: Yun Han Ling

Abstract: Coking wastewater produced in the coking process is poisonous and difficult to be degraded. Coking wastewater was treated by fixed bed reactors of metallization pellets with high carbon (MPHC). In this paper, it studies the effect of removing phenols, cyanide, chemical oxygen demand（COD）and ammonia nitrogen in coking wastewater by MPHC. The results show that MPHC has good degradation effect on phenols and cyanide in coking wastewater, and the degradation rate reaches to 99.88% and 99.81% respectively; and has certain degradation effect on COD, the degradation rate is 70.61%; has poor degradation effect on ammonia nitrogen. The results of FT-IR indicate that the degradation of organic pollutants in coking wastewater by MPHC is not simply adsorption, but is removed completely.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Titanium dioxide nanotube array films on aluminum plate were prepared via liquid phase deposition (LPD) method. The samples were characterized by field-emission scanning electron microscopy (FE-SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The results show that the nanotube array films’ morphology depends on the anodic aluminum oxide (AAO) structure and deposition time. The titanium dioxide nanotube’s outside diameter is about 250 nm, the wall thickness is approximately 40 nm. The as-prepared TiO₂ array films are amorphous and anatase appeared after calcining at 400°C for 2 hrs. FT-IR spectrum indicates that there are lots of hydroxyl groups on the surface of AAO. When AAO was immersed into 0.1 M (NH₄)₂TiF₆ solution at room temperature, AAO was dissolved in the solution and the holes became wide. The hydrolysis reaction was shifted to the right-hand side, TiO₂ particles locked in-situ on the inner surface of the anodic alumina pore induced by hydroxyl group, thus nanotube array film was obtained.

Abstract: 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.

Abstract: 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.