Papers by Author: Yan Fang Shen

Abstract: TiO₂ is a promising photocatalyst with great potential for environment purification and energy conversion. TiO₂ coatings have more advantages over powders in practical use. Cold spraying is an ideal technique to fabricate TiO₂ coatings because of its low heat input compared with thermal sparing which may induce undesirable phase transformation from anatase to rutile. The paper will give a short introduction on recent development of TiO₂ coatings by cold spraying. Then, the factors affecting the quality of coating should be analyzed. And finally, the bonding mechanism of cold sprayed TiO₂ coating on metal substrates will also be proposed.

Abstract: Nitrogen-doped titania nanotubes (TiO2-xNx NTs) were synthesized by the soft chemical process, in which nitrogen-doped titania nanopowders (TiO2-xNx NPs) reacted with strong alkaline solutions (10M). The properties of TiO2-xNx NTs were examined. Experiments on the photodegradation of methylene blue (MB) and sulfosalicylic acid (SSA) were also carried out under visible light irradiation.

Abstract: Nano-sized nitrogen-doped Ti-W mixed oxides (N-TiO2-x%WO3) were prepared by soft chemical method, and their intrinsic characteristics were investigated using XRD, TEM, N2 adsorption and desorption isotherms, UV-Vis diffuse reflectance spectra and XPS. Experiments on photodegradation of Methylene Blue (MB) under visible light irradiation were carried out to evaluate the photocatalytic abilities of N-TiO2-x%WO3. Chemical Oxygen Demand (COD) analysis was also performed to evaluate the mineralization abilities of N-TiO2-x%WO3. It is shown that the N-TiO2-x%WO3 exhibited higher COD removing rates compared with Degussa P25. The color bleaching rates of N-TiO2-x%WO3 were equal to that of Degussa P25. The enhanced photocatalytic activities were probably related to the strong absorption abilities of the N-TiO2-x%WO3.

Abstract: Tantalum dioxide and nitrogen co-doped titanium dioxide nanopowders, denoted as (Ta2O5, N) co-doped TiO2, were fabricated by a high-energy ball miller using TiO2, Ta2O5 and urea as raw materials. Experiments on the photocatalytic activities of the (Ta2O5, N) co-doped TiO2 were carried out in the form of photodegradation of methylene blue (MB) in aqueous solution under visible light irradiation. Enhanced photocatalytic activities were observed for the (Ta2O5, N) co-doped TiO2 than commercial Degussa P25. Besides, physical, chemical and optical properties, including XRD, DRS, and XPS were detected to analyze the origins for the enhanced photocatalytic activities of the prepared samples.

Abstract: Nitrogen-doped titania nanoparticles were co-prepared by sol-gel and mechanical-alloying method. Raman spectroscopy was used to investigate the microstructure information of the nitrogen-doped titania nanoparticles. Besides, XPS, ESR and UV-vis absorption spectra were also analyzed as supplementary means. At first blue then red shift of 142 cm-1 peak was observed as the annealing temperatures increased. The possible reasons for the shift were discussed.