In this paper, we prepare TiO2 fibers by electrospinning and modify them using nitrogen at high temperatures. Experimental Materials The precursor for electrospinning was prepared by the sol–gel method. In a typical synthesis, 1.5 g of polyvinylpyrrolidone (PVP, molecular weight = 1,300,000) was dissolved in 20 mL of ethanol, after which 5 mL of acetic acid and 5 mL of tetrabutyl titanate were added to the above solution under magnetic stirring. After 1 h of stirring at 70°C in a water bath, the resultant orange solution was used as the electrospinning precursor. Methylene blue (MB; concentration 20 mg/L in distilled water) was used as a model pollutant to measure photocatalytic activity of the TiO2

HKI-272 molecular weight catalysts. P25 TiO2 (Degussa; anatase phase, 20%; rutile phase, 80%) was used as standard photocatalytic material. Electrospinning In the electrospinning procedure, the precursor solution was loaded into a 5-mL syringe with a stainless steel needle. An electric voltage of 15 kV was supplied between the needle and the collection target covered with aluminum foil. The distance between the needle and the collection target was 15 cm. A flow rate of 0.15 mm/min was supplied by a syringe pump. PCI-34051 research buy A white nanofiber mat was prepared by electrospinning. PVP-Ti composite fibers were prepared by electrospinning. The as-obtained fibers were calcined at a temperature range of 500°C to 650°C at a heating rate of 1°C/min. Preservation heating was performed for 4 h under flowing

N2 and NH3 surroundings. Characterization The PVP-Ti composite fibers and calcined Ti fibers were characterized by various techniques

such as thermogravimetry-differential Sapanisertib cell line scanning calorimetry (TG-DSC), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), fluorescence microscopy-scanning electron microscopy (FM-SEM), transmission electron microscopy (TEM), and UV-Visible (UV–vis) spectrophotometry selleck diffuse reflectance spectroscopy. The TG-DSC instrument was operated at a heating rate of 10°C/min in air and used to determine the thermal decomposition behavior of PVP-Ti composite fibers. Phase analysis of calcined fibers was performed using a Rigaku D/max-rA (Rigaku Corporation, Tokyo, Japan) 12 kW x-ray powder diffractometer using CuKα radiation (2θ = 10° to 80°). XPS spectra were recorded by a Thermo Fisher ESCALAB 250 Xi XPS instrument (Thermo Fisher Scientific, Hudson, NH, USA). The morphology and size of the calcined Ti fibers were observed by FM-SEM and TEM. UV–vis diffuse reflection spectra were used to determine the absorption spectra of the heat-treated fibers. Finally, the catalytic activity of the calcined fibers was detected by UV–vis. Photocatalytic experiment The photocatalytic activity of the calcined fibers was investigated by the degradation of a standard solution of MB in a photochemical reactor. The photocatalytic reactor contained a lamp with a 500-W UV tube manufactured by Shanghai Bilon Instruments Co., Ltd. (Minhang District, Shanghai, China).