Huiqin An

Iron-coated TiO2 nanotubes and their photocatalytic performance

Iron-coated TiO2 nanotubes are successfully synthesized by treating hydrogen titanate nanotubes with Fe(OH)3 sol. The products are characterized with transmission electron microscopy, atomic absorption spectrometer, X-ray diffraction, Raman spectroscopy, UV-visible absorption spectroscopy and nitrogen adsorption. The photocatalytic performance is evaluated by the photocatalytic degradation rates of methyl orange in aqueous solution under UV-vis light irradiation. The effects of the calcination temperature, concentration of Fe(OH)3 sol and pH value of solution on the photocatalytic performance of iron-coated nanotubes are investigated. The results reveal that the iron-coated nanotubes exhibit better thermal stability and photocatalytic performance than their precursors. The iron-coated nanotubes can keep the nanotubular structure when calcined at 400 °C, and the specific surface area does not decrease sharply. We also discover that the pH of the solution has an obvious influence on the photocatalytic activity of iron-coated nanotubes. When the pH is about 2.4, the maximum photodegradation rate appears; moreover, the recycled catalyst still shows good photodegradation activity.

Characterization of Pt catalysts supported by three forms of TiO2 and their catalytic activities for hydrogenation

Three forms of TiO2, commercial TiO2 powder, hydrogen titanate nanotubes obtained by hydrothermal treatment, and the thermally stable TiO2 nanotubes prepared by treating hydrogen titanate nanotubes with a sol containing titanium, were used as supports, and Pt nanoparticles were deposited on the supports via the photodeposition method. The catalytic performances of as-prepared and calcined Pt/TiO2 catalysts for the hydrogenation reaction of cyclohexene were evaluated. The results showed that the effects of the support and calcination temperature on the catalytic performances of Pt/TiO2 catalysts were obvious and significant. The thermally stable nanotubular TiO2-supported Pt catalyst exhibited better catalytic performance than the other TiO2-supported Pt catalysts. In addition, it was discovered that the calcination can enhance the catalytic activity of Pt/TiO2 for hydrogenation greatly.

Design, synthesis of uniform Au nanoparticles modified Fe2O3–TiO2 coaxial nanotubes and their enhanced thermal stability and photocatalytic activity

Iron-coated TiO2 coaxial nanotubes (Fe2O3/TiO2 nanotubes) synthesized by treating TiO2 nanotubes with Fe(OH)3 sol are used as a support, and gold nanoparticles are loaded on the support by a simple one-pot strategy using lysine as both the linker and the capping agent. The obtained Au/Fe2O3/TiO2 hybrid nanotube materials are characterized by TEM, XRD, XPS, UV-vis, AAS and nitrogen adsorption. The photocatalytic performance is evaluated by the photocatalytic degradation rates of methyl orange under UV light irradiation. The effects of Au content, the absence/presence of lysine and Fe2O3, the pH value of solution and the addition amount of H2O2 to solution on the photocatalytic performance of Au/Fe2O3/TiO2 nanotubes are investigated. The results reveal that gold nanoparticles capped by lysine can be highly dispersed on the supports against aggregation, and the products exhibit higher thermal stability and photocatalytic activity in comparison to pristine TiO2 nanotubes.

Preparation, characterization and photocatalytic performances of materials based on CS2-modified titanate nanotubes

CS2-modified titanate nanotubes (CS2/TiO2-NTs) are fabricated by reaction of CS2 and Ti-O−Na+ species on titanate nanotubes. Pb2+ ions are coated on the modified nanotubes by ion exchange (Pb/CS2/TiO2-NTs). The products are characterized by means of nitrogen adsorption-desorption isotherms at 77 K (BET method), transmission electron microscopy (TEM), X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), atomic absorption spectrometry (AAS), and diffuse reflectance spectroscopy (DRS). The photocatalytic performances of the products are evaluated by monitoring their catalytic activities for degradation of methyl orange under UV light irradiation. The effects of calcination temperature and atmosphere on the photocatalytic performance are investigated. The results reveal that the photocatalytic activities of CS2/TiO2-NTs and Pb/CS2/TiO2-NTs are far higher than that of primary nanotubes, and the optimum calcination temperature is 500 °C under N2 atmosphere. It is also discovered that physically adsorbed Pb2+ ions affect the photocatalytic activity of Pb/CS2/TiO2-NTs obviously. The photocatalytic activity of washed Pb/CS2/TiO2-NTs is higher than that of the unwashed one under the same thermal treatment and reaction conditions.