Well-aligned TiO2 nanorod arrays (TNAs) were prepared on pretreated quartz substrates via hydrothermal method.The effect of the different preparation conditions on the growth morphologies of TNAs was systematically investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM).The photocatalytic properties were tested by photodegradation of a methyl blue solution.It is demonstrated that the hydrothermal reaction conditions,such as precursor concentration,hydrothermal reaction temperature,and hydrothermal reaction times,can greatly affect the growth of TNAs.Controlling the preparation process,TNAs with 2 μm in length and 140-170 nm in diameter and well-aligned orientation have been successfully prepared.The photocatalytic experiment results indicate that TNAs have much better photocatalytic activity than TiO2 nanoparticles.
Well-aligned hexagonal ZnO nanotubes (NTs) arrays were synthesized on pretreated indium tin oxide (ITO) substrates by a simple hydrothermal method. The morphology and structure of the products were characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). A new method of substrate pretreatment was introduced to prepare ZnO coated films. The size of ZnO seeds and the formation rate of ZnO NTs were investigated. Further, the mechanism of the preparation of ZnO NTs was discussed. The photoluminescence (PL) spectrum measurement shows fairly internal defects existing in ZnO nanotubes.
Nano TiO2/Fe3O4 composite particles with different molar ratios of TiO2 to Fe3O4 were prepared via sol-gel method. X-ray diffraction, transmission electron microscopy, and vibration sample magnetometry were used to characterize the TiO2/Fe3O4 particles. The photocatalytic activity of the particles was tested by degrading methyl blue solution under UV illumination (254 nm). The results indicate that with the content of TiO2 increasing, the photocatalytic activity of the composite particles enhances, while the magnetism of the particles decreases. When the molar ratio of TiO2 to Fe3O4 is about 8, both the photocatalytic activity and magnetism of the TiO2/Fe3O4 particles are relatively high, and their photocatalytic activity remains well after repeated use.
Large-scale single-crystalline SnO2 nanocauliflowers were successfully synthesized using a hydrothermal growth method without any template. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), en- ergy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). FE-SEM images show that the as-grown SnO2 nanocauliflowers are constructed of tetragonal prisms with a width of 500-600 nm. XRD, EDS, and SAED results indicate that the as-grown SnO2 nanocauliflowers are single crystalline with the tetragonal rutile crystalline structure. The growth mechanism of SnO2 nanocauliflowers is also preliminarily discussed on the basis of different Sn(OH) 62- concentrations, and it is found that Sn(OH) 62- concentration plays an important role in determining the shape of the prepared SnO2. Room temperature photoluminescence was further carried out on SnO_2 nanocauliflowers to investigate their optical properties. An intense blue luminescence centered at a wavelength of 424 nm is observed in the as-grown SnO2 nanocauliflowers.
Nanostructured Fe-doped titanium dioxide was synthesized from titanium containing electric furnace molten slag(TCEFMS)by using an alkali fusion,followed by a hydrolyzation-acidolysis-calcination route.The efects of alkali/slag mass ratio,calcinating temperature,calcinating time,and water/slag mass ratio on the extraction efciency and purity of products were systematically studied in this paper.It is indicated that the best extraction efciency of nanostructured Fedoped titanium dioxide is 99.35%,when the molten slag is calcinated at 700 C for 1 h with the mass ratio of alkali/molten slag of 1.5:1.The influence of alkali/slag mass ratio on the photocatalytic activity of final products was evaluated by the photodegradation of methyl blue under visible light irradiation.A maximum photodegradation efciency of 88.12%over30 min was achieved under the optimum conditions.
