No abstract

No abstract

TiO2 nanotube arrays were successfully synthesized by the anodization method of Ti foils in electrolyte containing the mixtures of ethylene glycol (EG), ammonium fluoride (0.3 wt % NH4F) and deionized water (2 Vol % H2O). A constant dc power supply at 50 V was used anodization process with different anodizing times. The resultant samples were annealed at 450 °C for 2 h. TiO2 nanotube arrays were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The prepared TiO2 NTs has diameter in 50-200 nm. The minimum of diameter TiO2 nanotube arrays was approximately 50 nm for 1 h of anodization process.

Monoclinic BiVO4 photocatalyst films decorated on glass substrates were successfully fabricated via a dip-coating technique with different annealing temperatures of 400 °C, 450 °C, 500°C, and 550 °C. All of the physical and chemical properties of as-prepared BiVO4 photocatalyst film samples were investigated using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectra techniques. The results revealed that the as-prepared BiVO4 photocatalyst film samples retained a monoclinic phase with an average particle size of about 50 – 100 nm. Moreover, the BiVO4 photocatalyst film samples showed a strong photoabsorption edge in the range of visible light with the band gap energy of 2.46 eV. The photocatalytic activities of all the film samples were tested by the degradation of model acid orange 7 under visible light irradiation. The BiVO4 photocatalyst film sample annealed at a temperature of 500 °C showed the highest photoactivity efficiency compared with other film samples, reaching up to 51%within 180 min. In addition, the stability and reusability of BiVO4 photocatalyst film sample made with an annealing temperature of 500 °C did not show loss of photodegradation efficiency of acid orange 7 after ten recycles. A likely mechanism of the photocatalytic process was established by trapping experiments, indicating that the hydroxyl radical scavenger species can be considered to play a key role for acid orange 7 degradation under visible light irradiation.

In the present work, the molten-salt method was applied to synthesize 0.948K0.5Na0.5NbO3–0.052LiSbO3 powder for the first time. Characteristics of the powder were investigated. Based on X-ray diffraction technique, pure perovskite phase was observed at a calcination temperature of 700 oC which is lower than that required by the conventional solid-state reaction technique for ∼200 oC. Raman spectroscopy technique showed that the powder had an orthorhombic symmetry which consistent with the X-ray diffraction results. The powder exhibited very fine grain with narrow size distribution. Particle size of the obtained powders increased with increasing calcination temperature. Therefore, the molten-salt method is a simple and effective method to synthesize 0.948K0.5Na0.5NbO3 – 0.052LiSbO3 powder.