Qiuye Li

AgBr modified TiO2 nanotube films: highly efficient photo-degradation of methyl orange under visible light irradiation

Anatase TiO2 nanotube film was prepared by calcination of the orthorhombic titanic acid nanotube at 400 °C. To expand the light absorption, AgBr nanoparticles were sensitized on TiO2 film. The AgBr–TiO2 nanotube film showed a high activity for MO photo-degradation under visible light irradiation. Moreover, the photocatalytic activity was further improved a lot after annealing of the AgBr–TiO2 nanotube film.

A new method of preparation of AgBr/TiO2 composites and investigation of their photocatalytic activity

Silver bromide/titanium dioxide composites were first prepared using titanic acid nanobelts (TAN) as the TiO2 source. First, TAN reacted with AgNO3 to prepare Ag-incorporated TAN by the ion-exchange method, and then AgBr/TAN was obtained after adding NaBr. Finally, AgBr/TAN was transformed to AgBr/TiO2 composites by calcination. The post-treated calcination would not only convert TAN to TiO2 (H2Ti2O4(OH)2xa0→xa02H2Oxa0+xa02TiO2), but also increase the effective contact between AgBr and TiO2, further to improve the separation of photo-generated electron-holes. The advantage of this preparation method is the small particle size (ca. 10–20xa0nm) and well dispersion of AgBr on the surface of TiO2, and close contact between AgBr and TiO2. The effect of the different calcination temperature on the morphology, structure, and properties of AgBr/TiO2 composites was investigated in detail. The AgBr/TiO2 composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and ultraviolet–visible diffuse reflectance spectra (UV–Vis DRS). Comparing with pure TAN, AgBr, and AgBr/P25 mixture, the AgBr/TiO2 composites exhibited enhanced photocatalytic activity in decomposition of methyl orange (MO) under visible light irradiation.

Fe0/Graphene Nanocomposite as a Catalyst for the Viscosity Reduction of Heavy Crude Oil

Fe0/graphene nanocomposites were prepared via a thermal polymerization method and used as a catalyst to reduce the viscosity of heavy crude oil. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms and thermal analysis. Their performance on the aquathermolysis of heavy crude oil was assessed in an autoclave. Under the reaction conditions of 200°C and 24 h, the viscosity of the oil was remarkably reduced when the catalysts were added.

Pseudo and true visible light photocatalytic activity of nanotube titanic acid/graphene composites

Nanotube titanic acid/graphene (NTA/Gr) composites were prepared by an easy hydrothermal treatment of graphene oxide (GO) and NTA in a mixed solvent of ethanol–water. As-prepared NTA/Gr composites and GO were characterized by means of Fourier transform infrared spectrometry, X-ray diffraction, diffuse-reflection spectrometry, thermal analysis, and transmission electron microscopy. Besides, the photocatalytic activities of as-prepared NTA/Gr composites were evaluated by monitoring the degradation of methyl orange (MO) under visible light irradiation. It has been found that extending hydrothermal reaction time (24xa0h instead of 3xa0h) leads to great changes in the morphology and crystal structure of as-prepared composites. Namely, the orthorhombic NTA (ca. 10xa0nm in diameter) in the composite transformed to anatase TiO2 particle (ca. 20–30xa0nm in diameter) while the Gr sheets (with micrometers-long wrinkles) in it transformed to a few Gr fragments (ca. 50xa0nm in diameter). Correspondingly, the NTA/Gr composite transformed to titanium dioxide/graphene (TiO2/Gr) composite. In the meantime, pure GO only has adsorption effect but it has no photocatalytic activity in the visible light region. Nevertheless, increasing Gr ratio results in enhanced visible light absorption capability and photocatalytic activity of NTA/Gr composites as well as the TiO2/Gr composites. This demonstrates that the true visible light photocatalytic activity of NTA/Gr composites as well as the TiO2/Gr composites for the degradation of MO is not as excellent as expected, and their high apparent activity is attributed to the strong adsorption of MO on the composites.