静电纺丝法制备Fe3+/TiO2纳米纤维及表征

以聚乙烯吡咯烷酮(PVP)为纤维模板,钛酸四丁酯(Ti[O(CH2)3CH3]4)和Fe3+为前驱体,乙醇为溶剂,醋酸为催化剂,采用静电纺丝法制备不同含铁量的复合纳米纤维Fe3+/TiO2,经500℃煅烧得到以锐钛矿为主的Fe3+/TiO2纳米纤维。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)分别表征了Fe3+/TiO2纳米纤维的形貌与晶态,计算了样品的晶粒尺寸和锐钛矿所占的比例,并比较了5%Fe3+/TiO2纳米纤维、5%Fe3+/TiO2粉体以及纯TiO2纳米纤维三者光催化降解亚甲基蓝(MB)的效果。研究表明:由静电纺丝法制备的5%Fe3+/TiO2纳米纤维的光催化降解效果比相同含铁量的粉体的降解效果好,TiO2纳米纤维比5%Fe3+/TiO2纳米纤维的光催化活性高。     

碳纤维负载钐掺杂纳米TiO_2复合材料的制备与表征

采用静电纺丝法和热处理工艺制备了纳米碳纤维负载掺杂1.5%(摩尔分数)Sm的纳米Ti O2复合材料(Sm-Ti O2/CNFs),利用SEM、EDX、TEM、FTIR和XRD对其组成和结构进行了表征,并以甲基橙为降解对象,考察了Sm-Ti O2/CNFs复合材料在紫外光照射下对甲基橙的光催化降解效果。结果表明,掺杂Sm3+的Ti O2以锐钛矿晶型均匀分散在碳纳米纤维的表面和内部,质量分数为20%左右;相对于未掺杂的Ti O2/CNFs样品,Sm-Ti O2/CNFs的光催化活性提高约37%。     

Adsorption behavior of Cu(II) onto titanate nanofibers prepared by alkali treatment

Novel low-cost adsorbents of titanate nanofibers with formula Na(x)H(2-x)Ti(3)O(7) · nH(2)O have been prepared by alkali treatment for Cu(II) removal from aqueous solutions. The nanofibers have structures in which three edge-shared TiO(6) octahedras join at the corners to form stepped, zigzag Ti(3)O(7)(2-) layers. The sodium cations located between the layers are exchangeable. The results of batch adsorption experiments suggest that the nanofibers with high sodium content can be effective adsorbents for Cu(II) removal. Effects of several important factors such as Na amount in adsorbents, pH, temperature, contact time and initial concentration are systematically studied. Results show that the adsorption is highly pH-dependent and the removal is almost complete (99.8%) for initial concentration under 100mg/l at pH 4. Equilibrium adsorption follows Langmuir isotherms well and the maximum Cu(II) uptake calculated is 167.224 mg/g. The adsorption kinetics can be explained by pseudo-second-order model well and the time needed for equilibrium is 180 min. Thermodynamic study indicates that the adsorption is spontaneous and endothermic. Desorption of Cu(II) from adsorbents using EDTA-2Na solutions exhibits a high efficiency and the adsorbents can be used repeatedly. These results demonstrate that the titanate nanofibers are readily prepared, enabling promising applications for the removal of Cu(II) from aqueous solutions.     

Fabrication and hydrogen sensing properties of interlinked ribbon-like TiO2 films

Interlinked ribbon-like TiO2 films were prepared by micro-arc oxidation (MAO) process and subsequent chemical-treatment of titanium substrate. The chemical-treatment included two steps: firstly, alkali treatment was performed on the surface of the porous TiO2 films, and then the samples were ion-exchanged in acid aqueous solution. The phase and microstructure of the samples were characterized by XRD, FE-SEM and TEM. It is found that ribbon-like sodium titanate is formed by alkali treatment, and its morphology remains unchanged after acid-treatment. However, the phase compositions of the samples surface change into TiO2 (MAOC-TiO2) after heat-treatment above 500 degrees C. The hydrogen sensing properties at low concentrations were investigated. The result shows that such ribbon-like TiO2 films present high sensing properties at a low temperature.     

Development of photocatalytic TiO2 nanofibers by electrospinning and its application to degradation of dye pollutants

We have developed photocatalytic TiO2 nanofibers for the treatment of organic pollutants by using electrospinning method. We found that the optimized electrospinning conditions (electric field and flow rate) were 0.9 kV cm(-1) and 50 microL min(-1). After annealing at 550 degrees C for 30 min, we fabricated TiO2 nanofibers (average 236 nm thick) with anatase crystalline phase. To increase photocatalytic activity and effective surface area, we coated photocatalytic TiO2 particles on the TiO2 nanofibers by using sol-gel method. The degradation rate (k'=85.4x10(-4) min(-1)) of composite TiO2 was significantly higher than that (15.7x10(-4) min(-1)) of TiO2 nanofibers and that (14.3x10(-4) min(-1)) of TiO2 nanoparticles by the sol-gel method. Therefore, we suggested that the composite TiO2 of nanofibers and nanoparticles be suitable for the degradation of organic pollutants.     

纳米TiO2薄膜光催化剂的制备及性能研究

以钛酸四丁酯作为前驱体,用溶胶一凝胶法,在玻璃载体上煅烧制备了纳米TiO2薄膜光催化剂,利用扫描电子显微镜（SEM）、X射线衍射（XRD）等表征技术研究了TiO2薄膜的形貌和特性,其光催化性能用4支20W紫外石英杀菌灯照射TiO2薄膜分解亚甲基兰染料溶液表征,结果表明,该催化剂具有锐钛班红石混合晶相和纳米花状结构,纳米TiO2薄膜的光催化能力随着镀膜层数的增加而增加。     

Hydrothermal synthesis and photocatalytic activity of anatase TiO2 nanofiber

TiO2 nanofiber consisting of 15 +/- 5 nm anatase grains was synthesized by hydrothermal treatment of fibrous hydrogen titanate precursor at 180 degrees C for 20 h. The hydrogen titanate precursor was synthesized by hydrothermal treatment of commercial P25 TiO2 powder in 10 M NaOH at 200 degrees C for 20 h followed by soaking in 0.1 M HNO3 to perform ion exchange between the as-synthesized Na titanate and H. By controlling pH of the solution during hydrothermal treatment of the hydrogen titanate precursor, pure anatase TiO2 nanofiber was obtained. Its band-gap energy determined from the onset of diffused reflectance spectrum was 3.19 eV which is equal to that of anatase TiO2 powder. The TiO2 nanofiber showed higher photodecomposition efficiency than the Cotiox KA-100 TiO2 but lower than the P25 TiO2. Photodegradation is the predominant process for 'Reactive blue 171' removal.     

Simple fabrication of carbon/TiO2 composite nanotubes showing dual functions with adsorption and photocatalytic decomposition of Rhodamine B

Carbon/TiO2 composite nanotubes were fabricated via a very simple electrospinning process and their dual functionalities of adsorptivity and photocatalytic activity were evaluated using Rhodamine B (RhB) as a model organic pollutant. A poly(vinyl alcohol) (PVA) aqueous solution was directly electrospun into a coagulation bath containing titanium (IV) tetraisopropoxide (TTIP) solution so that PVA-core/TiO2-shell composite nanofibers were formed through the in situ sol-gel reaction of TTIP. The carbon/TiO2 composite nanotubes were then fabricated by heat treatment of composite nanofibers under nitrogen atmosphere. By using several characterization methods, we confirmed that the resultant nanotubes consisted of anatase TiO2 nanocrystallites embedded in a carbonaceous matrix. The prepared nanotubes exhibited fast adsorption of RhB with high capacity compared with a commercial porous carbon, and they also showed the photocatalytic decomposition activity for the dye molecules under UV irradiation comparable to the degradation by P-25 and ST-01 (commercial TiO2). Finally, the carbon/TiO2 composite nanotubes exhibited several cycle performances of adsorption-photodegradation for RhB. This indicates that the composite nanotubes can adsorb and photodecompose organic pollutants repeatedly without additional activating processes.     

掺锡TiO2复合薄膜的制备和光催化性能的研究

通过溶胶-凝胶工艺在玻璃表面制备了均匀透明的掺锡锐钛矿型TiO₂光催化复合薄膜,用SEM、XRD、XPS等对薄膜进行了表征。薄膜中除含有Ti,O, Sn等元素外,还存在一定量的来自有机前驱物未完全燃烧的C元素和从玻璃表面扩散到薄膜中的Na和Ca元素。甲基橙水溶液的光催化降解实验表明:掺锡TiO₂复合薄膜的表观降解速率常数明显高于未掺锡TiO₂薄膜的表观降解速率常数,这为进一步提高TiO₂薄膜的光催化活性开辟了新的途径。      

Electron beam irradiation effect on the photocatalytic activity of TiO2 on carbon nanofibers

The electron beam (EB) irradiation effects of TiO2 deposited on carbon nanofibers (CNFs) were studied aiming the improvement of the photocatalytic activity. The EB irradiation contributed to an increase in crystallinity of the anatase resulting an improvement of the photocatalytic activity through the oxidation (ionization) of the doped TiO2 and leading to uniform distribution TiO2 particles on the CNFs surface. The photoactivity of the catalyst was measured by the decoloration of the methylene blue (MB) with time under UV irradiation.     

Photocatalytic properties of silver nanoparticles decorated nanobranched TiO2 nanofibers

In this study, nanobranched TiO2 nanofibers and silver loaded nanobranched TiO2 nanofibers were prepared by electrospinning technique followed by TiCl4 aqueous solution treatment and silver photodeposition method. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to investigate the morphology of the products. X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) were conducted on the samples to study their chemical composition as well as crystallographic structure. The photocatalytic activities of these produced nanofibers were examined with two organic dyes, methylene blue and methyl orange, under ultraviolet (UV) light irradiation. The effect of nanobranches and silver modification on TiO2 nanofibers was revealed in the photocatalysis process. The photocatalytic degradation rates of silver loaded on nanobranched TiO2 nanofibers were 1.6 and 1.7 times as that of pure TiO2 nanofibers in the presence of methylene blue and methyl orange, respectively, which indicated silver nanoparticles combined nanobranches modified on the surface of TiO2 nanofibers could enhance the photocatalytic ability.     

银掺杂TiO2光催化剂的制备及光催化性能研究

采用溶胶-凝胶法,以钛酸四丁酯、硝酸银为原料制备了不同银含量掺杂TiO2光催化剂,并以TG-DTA、XRD、TEM对样品进行了表征,XRD结果显示,掺杂银TiO2光催化剂为锐钛矿型,银掺杂量较低时,银均匀分布在TiO2的表面,在掺杂量为4%时,出现银的团聚。光催化亚甲基蓝结果表明,银掺杂TiO2光催化剂比未掺杂TiO2降解率明显提高,在2%银掺杂TiO2光催化剂用量为25mg,pH值为6～8,降解时间为120min,降解率可达93%。     

层层组装技术制备纳米级TiO_2/聚电解质复合中空纤维催化剂

采用静电纺丝技术和层层组装技术制备了聚电解质/TiO2复合中空纳米纤维膜.通过控制PS纤维模板直径和吸附层数,TiO2中空纤维的直径和壁厚得到了很好的控制.在光催化降解乙醛性能实验中,TiO2中空纤维具有比P25更好的光催化性能.     

Effects of calcination temperature on microstructures and photocatalytic activity of titanate nanotube films prepared by an EPD method

Titanate nanotube films are fabricated on F-doped SnO(2)-coated glass substrates via an electrophoretic deposition method using hydrothermally prepared titanate nanotubes as precursors. The effects of calcination temperature on the microstructures and photoactivity of as-prepared titanate nanotube films are investigated and discussed. The results indicate that the intercalated sodium ions (Na(+)) in the as-prepared titanate nanotubes are easily removed during the electrophoretic deposition. The phase transformation of titanate to anatase and diffusion of Na(+) ions from glass substrates into films occur at 400?°C. With increasing calcination temperature, the crystallization of anatase enhances and sodium content in the films increases. At 500?°C, the tubular structure still holds and the films show the highest photocatalytic activity probably due to their good crystallization, large specific surface areas and tubular structures.     

Synthesis of anatase-silver nanocomposite fibers via electrospinning

There has been growing interest in new ways to produce composite nanofibers. Continuous TiO2 (anatase phase) nanofibers with silver nanoparticles were prepared successfully via sol-gel and electrospinning. A sol containing poly(vinyl pyrrolidone), titanium tetraisopropoxide, and silver nitrate was injected through a conductive capillary where high voltage was applied. As a result of electrospinning, continuous composite nanofibers were collected and they were calcined in air at 500 degrees C in order to complete the crystallization of anatase phase. The anatase-silver nanocomposite fibers were characterized with X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy.     

微波辐射溶胶-凝胶法制备TiO2薄膜及其降解铬黑T的活性

通过微波辐射溶胶一凝胶法（sol-gel）法在导电玻璃（ITO）基体上制备TiO2纳米薄膜光催化剂，考察不同加热方式、微波时间、酸处理、薄膜层数等对TiO2纳米粒子及薄膜的影响。以可见光谱（UV-VIS）、X射线衍射（XRD）对TiO2薄膜进行了表征，并通过薄膜光催化降解铬黑T溶液的性能进行了研究。实验表明，ITO玻璃表面的TiO2纳米薄膜经HNO3和微波处理后，因协同效应使薄膜的光催化活性大大增强。     

Novel carbon fiber/epoxy composite toughened by electrospun polysulfone nanofibers

Novel carbon fiber/epoxy composite toughened by electrospun polysulfone (PSF) nanofibers was prepared to enhance fracture toughness of the composite, and compared the morphology and toughness to those of composite toughened by PSF films prepared by solvent method. Polysulfone nanofibers with the average diameter of 230 nm were directly electrospun onto carbon fiber/epoxy prepregs to toughen the composite. SEM observations of the polysulfone nanofibers toughened composite revealed that polysulfone spheres with uneven sizes presented uniform dispersion through interleaves of the composite, which was different from those of composite toughened by PSF films. Mode I fracture toughness (G_IC) of the nanofibers toughened composite was 0.869 kJ/m² for 5.0 wt.% polysulfone nanofibers content, which was 140% and 280% higher than those of PSF films toughened and untoughened composite due to the uniform distribution of polysulfone spheres.     

Synthesis and morphology of electrospun PVA/PLZT composite and single phase PLZT nanofibers

Polyvinyl alcohol/lead lanthanum zirconate titanate (PVA/PLZT) composite nanofibers were prepared by the electrospinning method. The PLZT sol was prepared by using lead acetate trihydrate, titanium isopropoxide and zirconium propoxide molecular precursors based on sol-gel procedure. The influence of applied voltage, flow rate and needle-to-collector distance on the composite fiber morphology and diameters has been studied. The nanofibers were characterized by X-ray diffraction, TGA-DSC, FTIR spectroscopy and scanning electron microscopy (SEM). Single phase with perovskite structures PLZT nanofibers were also obtained by calcining the PVA/PLZT nanofibrous mat at 650 °C for 2 h. A linear correlation was observed between the single perovskite phase evolution and the calcination temperature.     

溶胶凝胶法制备的TiO2薄膜结构对光催化活性的影响

TiO2多孔纳米薄膜采用溶胶－凝胶法在普通载玻片上制得。薄膜的结构如孔径、孔分布和厚度可控制。通过稀醋酸的分解来测定锐钛矿TiO2多孔薄膜的结构对光催化活性的影响。     

Eu-doped titania nanofibers: processing, thermal behaviour and luminescent properties

Undoped and Europium-doped titania nanofibers have been fabricated by electrospinning technique, using a single multielement Titanium/Europium source. In this communication we present the synthesis, structural and spectroscopic characterisation of Eu-doped TiO2 nanofibers starting from polyvinylpyrrolidone, titanium tetraisopropoxide (Ti(OiPr)4) and Eu(hfa)3 x diglyme (Hhfa = 1,1,1,5,5,5-hexafluoroacetyacetone, diglyme = CH3O(CH2CH2O)2CH3). The chosen system allowed to investigate a wide compositional range, i.e., from 3 to 10% mol of Eu3+. Microstructure was studied by means of scanning electron microscopy (SEM), thermal behaviour followed by thermogravimetric and differential thermal analysis (TG-DTA). Phase analysis was performed by means of X-ray diffraction (XRD) and high temperature X-ray diffraction analysis (HT-XRD) up to 1100 degrees C. Luminescence properties were investigated by means of luminescence spectroscopy, using a laser excitation source at 395 nm. All electrospun materials consisted of randomly oriented nanofibers of fairly uniform diameter. The average fiber size was 80-100 nm and 40 nm for, respectively, Eu-doped and undoped TiO2 calcinated at 500 degrees C. The presence of Europium shifted toward higher values either the crystallization temperature of anatase and the anatase to rutile phase transition, the latter being accompanied by the formation of the Eu2Ti2O7 phase. The doped samples showed a strong luminescence of Eu3+ ions. The emission spectra were dominated by the 5D0 --> 7F2 emission, suggesting a notable distortion around the Eu3+ ions. The broadening of the bands pointed to the presence of a relevant inhomogeneous disorder around the Eu3+ sites. The Eu3+ doped TiO2 nanofibers showed a higher emission intensity with respect to the PVP/TiO2 ones.