TiO2纳米纤维的制备及其对染料的光催化降解性能

采用溶胶-凝胶与静电纺丝技术相结合的方法,将聚乙烯吡咯烷酮(PVP)和钛酸四正丁酯混合制得前驱体溶液,纺丝得PVP/TiO2复合纳米纤维,然后经500℃高温煅烧制备了TiO2纳米纤维光催化剂,通过其对阳离子艳红5GN、弱酸性黄GN、雷马素蓝RR等染料的降解研究了TiO2纳米纤维的光催化性能。利用扫描电子显微镜(SEM)观察了PVP/TiO2和TiO2纳米纤维的形貌结构;傅里叶变换红外光谱(FT-IR)证实了TiO2纳米纤维的形成;通过X射线衍射仪(XRD)对TiO2纳米纤维的晶型及晶粒大小进行了分析。结果表明制备出的TiO2纳米纤维形貌稳定,具有锐钛矿型TiO2结晶形态并对染料具有很好的光催化降解效果。     

新型纳米/亚微米纤维态催化剂的制备及表征

采用静电纺丝法以聚乙烯吡咯烷酮(PVP)和纳米T iO2为原料制备了一种新型纳米/亚微米纤维态催化剂。采用SEM、TEM、XRD、FT-IR对所制得的新型纳米/亚微米纤维态催化剂进行了表征,结果表明纤维直径随着纳米T iO2含量的增加而增加,纳米T iO2颗粒在PVP纤维基体中分散均匀,并且纳米T iO2颗粒和PVP分子形成了氢键。光催化性能测试结果表明纤维中纳米T iO2含量为20%时,紫外光照射80 m in对甲醛的光催化降解率达到了56.8%。     

液相还原两步法合成纳米铜的工艺研究

目的研究液相还原步法制备铜纳米颗粒过程中,工艺参数对铜纳米颗粒形貌尺寸的影响。方法在水体系下,先用葡萄糖将铜离子预还原为氧化亚铜,再使用次亚磷酸钠将氧化亚铜还原成纳米铜颗粒。分别改变反应过程中的PVP添加量、次亚磷酸钠的浓度以及加热温度,用场发射扫描电镜对所得的产物进行形貌观察。结果 PVP添加量与次亚磷酸钠浓度的提高,都使得铜纳米颗粒的尺寸逐渐减小,并且过量的PVP会造成铜纳米颗粒的团聚;然而随着温度的提高,铜纳米颗粒的尺寸先减小再增大。结论实验的最佳工艺参数为:PVP添加量为2 g,次亚磷酸钠浓度为1.2 mol/L,反应温度为60℃。此条件下所制备出的铜纳米颗粒分散性好、尺寸分布均匀,粒径为400 nm左右。     

静电纺丝制备Zn掺杂TiO_2复合纳米纤维

以聚乙烯吡咯烷酮(PVP)为络合剂与钛酸异丙酯、醋酸锌混合制得前驱体溶液,用静电纺丝法制得PVP/Ti(OCH(CH3)2)4/Zn(CH3COO)2复合纳米纤维,经700℃煅烧后,生成直径约300～400nm的Zn掺杂TiO2复合纳米纤维。研究结果表明,前躯体溶液的浓度、纺丝电压和接收距离对纤维的形貌和结构有较大的影响。通过差热-热重分析、红外光谱、扫描电镜、粉末X射线衍射等手段对纳米纤维进行了表征。在日光照射下以Zn掺杂TiO2复合纳米纤维光降解亚甲基蓝溶液,光降解效率优于TiO2纳米纤维。     

纳米TiO2的制备及其光催化活性

用高分子凝胶法制备纳米TiO2,研究了烧结温度对晶粒大小的影响以及粉体的平均粒径和光催化活性的关系.结果表明:高分子凝胶形成的小且均匀的网格限制了TiO2晶粒之间的接触和团聚,因此在较低温度下即可合成分散性好、平均粒径细小、粒径均匀且无团聚具有锐钛矿结构的纳米TiO2.随着煅烧温度的升高,纳米TiO2的平均粒径逐渐增大.纳米TiO2平均粒径的减小可提高其光催化活性以及对次甲基蓝的降解速率.适量的TiO2可以使次甲基蓝的降解率达到70%.     

超细PAN/PVP复合纳米纤维的制备及其性能研究

采用五因素五水平正交实验研究了溶液浓度、PAN/PVP比例、电压、接收距离和LiCl含量对聚丙烯腈(PAN)/聚乙烯吡咯烷酮(PVP)复合纳米纤维形貌的影响,成功的制备出了直径在100nm以下形貌优良的PAN/PVP复合纳米纤维,并通过XRD进行表征;并对PAN/PVP复合纤维在400℃下进行了低温碳化处理,采用四探针电导仪对纤维的电导率进行了研究。结果表明:制备PAN/PVP复合纤维最优参数组合为:浓度10wt%、PAN/PVP为5/5、电压10kV、接收距离20cm、LiCl含量0.5wt%;随溶液浓度增大,PAN/PVP复合纤维的结晶性能增大;PAN/PVP比例为5/5时,纤维的电导率最高,能达到1.2×10-2S/m。     

纳米TiO2表面吸附聚乙二醇及其分散稳定性的研究

通过四氯化钛水解法制备纳米TiO2，讨论聚乙二醇(PEG)在其水悬浮体系中的吸附行为．IR和吸附实验结果表明：纳米TiO2通过氢键吸附PEG，其表面吸附行为与PEG浓度、PEG分子量、pH值和晶粒尺寸等因素相关．吸附PEG以后，纳米TiO2颗粒的表面电荷和(电位发生变化．悬浮体系吸光度的变化和TEM分析表明：纳米TiO2吸附PEG后，增加了颗粒间的空间位阻作用，有效地阻止了纳米TiO2的团聚；但若PEG加入量达到过饱和，反而会破坏纳米TiO2的分散稳定性．     

纳米TiO2锂离子电池负极材料的溶剂热法制备及其电化学性能

本文采用溶剂热法,以四乙醇钛为主要原材料制备TiO2。结合X-射线衍射和扫描电镜等材料结构测试分析方法和恒电流充放电电化学测试技术,研究了添加表面活性剂聚乙烯吡咯烷酮(PVP)、溶剂热反应温度和高电导性气相生长碳纤维(VGCF)的添加对TiO2结构和电化学性能的影响。研究结果表明,本方法成功制备了纳米尺寸的锐钛矿TiO2,PVP的添加能改善TiO2颗粒的分散性。较低溶剂热反应温度下合成的TiO2颗粒尺寸较细,但团聚程度大,而较高的溶剂热反应温度使TiO2的颗粒尺寸长大,但团聚程度改善。通过添加表面活性剂、控制溶剂热温度和引入VGCF,本文获得的TiO2/C复合材料作为锂离子电池负极材料在1C、5C、10C和20C的放电倍率下容量分别可达220、180、150和120mAh/g,具有良好的倍率性能。     

热喷涂用纳米结构Al_2O_3/TiO_2/SiO_2团聚体粉末的研究

对喷雾干燥和不同温度热处理后Al2O3/TiO2/SiO2纳米团聚体粉末的流动性、松装密度及振实密度进行了测试,对喷雾干燥后的粉末进行了热重-差热分析,通过扫描电镜观察了粉末颗粒形貌和大小,采用X射线衍射分析了不同温度热处理后粉末的相组成,并对粉末的综合性能进行了比较。实验结果表明:在1000～1450℃热处理后的Al2O3/TiO2/SiO2纳米团聚体粉末颗粒仍近似球形,粒径在10～100μm之间。随着热处理温度升高,纳米团聚体大颗粒表面发生塌陷,大颗粒之间发生连接,大颗粒内部纳米颗粒明显长大。低于1250℃热处理后的粉末流动性好,振实密度高,适于等离子体喷涂制备纳米结构涂层。     

静电纺丝工艺对PVP/TEOS/硝酸盐复合纳米纤维成纤性状的影响

采用静电纺丝技术制备了PVP/[Sr(NO3)2+Mg(NO3)2+TEOS+Eu(NO3)2+Dy(NO3)2]复合纳米纤维,研究了不同静电纺丝工艺参数对其成纤性状的影响。结果表明:纤维的直径均随着电压、无机盐和PVP含量的增加呈现先减小后增大的趋势;随着纺丝液中无机盐含量的增加,纺丝液的黏度、表面张力和电导率均逐渐增大;随着PVP含量的增加,纺丝液的黏度、表面张力逐渐增大、电导率先减小后增大。SEM分析表明,当纺丝电压在13~15kV,纺丝液中无机盐含量为5%~6%,PVP含量为15%时,易获得形貌较好的复合纳米纤维。     

Preparation of poly(4-vinylphenol)/titanium dioxide composite and its application as a gate dielectric for organic thin-film transistors

Organic-inorganic composites can provide a unique feature combining superior dielectric properties of inorganic materials and solution processing capability of organic materials. In this study, poly(4-vinylphenol) (PVP) and titanium dioxide (TiO2) composite was prepared by mixing TiO2 nanoparticles in the PVP solution. In order to avoid severe gate-leakage currents in organic thin-film transistors (OTFTs) with such a composite gate dielectric layer, poly(oxyethylene)(20)-sorbitane monooleate was used as a surfactant for uniform dispersion of TiO2 particles. The dispersion stability of TiO2 nanoparticles in the composite solutions was confirmed by observing its sedimentation time in the composite solutions. The composite dielectric film, fabricated by means of simple spin-coating, provided an enhanced dielectric property and contributed to reducing the threshold voltage of OTFT, without augmenting the gate-leakage current. These results demonstrate that the fabricated composite dielectric film is essentially eligible for low-voltage operating OTFTs.     

Preparation and characterization of chitosan/poly(vinyl alcohol)/poly(vinyl pyrrolidone) electrospun fibers

Ultrafine fibers of chitosan/poly(vinyl alcohol)/poly(vinyl pyrrolidone) (CS/PVA/PVP) were prepared via electrospinning. The structure and morphology of CS/PVA/PVP ultrafine fibers was characterized by the Fourier transform infrared (FT-IR) spectroscope and scanning electron microscope (SEM). Furthermore, the effects of the concentration of PVA, PVP and the electrospinning voltage on the morphology of ultrafine fibers were investigated the the SEM. When the concentration of PVA was at the range of 30wt%–40wt%, ultrafine fibers could be obtained. The diameter distributions of ultrafine fibers decreased when the electrospinning voltage increased from 20 to 30 kV. The rough surface fibers could be obtained after etching with CHCl₃.     

Preparation of PVP/MEH-PPV composite polymer fibers by electrospinning and study of their photoelectronic character

Ultrafine polyvinylpyrrolidone (PVP)/poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) composite fibers were successfully prepared by electrospinning of PVP/MEH-PPV blend solutions in solvent mixtures of 1,2-dichloroethane/chlorobenzene. Composite polymer fibers with smooth surface were obtained using solutions in which MEH-PPV's concentration was 1.0 (wt.%). Compared with the MEH-PPV solution and bulk, PVP/MEH-PPV fibers show a significant blue shift, a stronger intensity of fluorescence and a higher surface photovoltage (SPV). The morphology of fibers has been characterized by scanning electron microscopy (SEM) and fluorescence microscopy.     

静电纺丝法制备金纳米粒子/PVP复合纳米纤维

采用水合肼还原一定浓度氯金酸溶液的方法,在聚乙烯吡咯烷酮(PVP)作保护剂的乙醇/水溶液中,成功制备出粒度较小,且高度分散的金溶胶,紫外吸收光谱证实了溶液中金纳米粒子的存在.采用静电纺丝技术制备了AuNs/PVP复合纳米纤维.采用扫描电镜(SEM)和X射线衍射(XRD)等分析手段对纤维的表面形貌等进行了表征.由扫描电镜...     

Electrospun Proficient Polymer Based Nano Fibers with Ceramic Particles

Cobaltite of magnesium, embedded in polyvinylpyrrolidone (PVP) polymeric fibers forming nanocomposite were synthesized by combining conventional sol-gel method with electrospinning method. Ultrathin diameter polymer fibers containing nanoregime ceramic particles were obtained by varying various process parameters like voltage, concentration, feed rate, distance between nozzle tip and base plate on an indigenously assembled electrospinning unit. Polyvinylpyrrolidone (PVP) and polyvinylalcohol (PVA) polymeric fibers in nanoregime were also synthesized separately and the effect of the process parameters was observed on the fiber thickness and continuity. Characterization was done to verify the synthesis parameter effect on structural morphology of polymer based nanofiber composite. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were used as tools for study of structural morphology and its correlation with process parameters.     

γ-Bi2O3/TiO2复合纤维的制备及光催化性能

采用静电纺丝技术与溶剂热法相结合制备了γ-Bi2O3/TiO2复合纤维光催化材料.利用X射线衍射(XRD)、扫描电镜(SEM)、电子能谱(EDS)、透射电镜(TEM)、高分辨透射电镜(HRTEM)和紫外–可见吸收光谱(UV-Vis)等分析测试手段对材料进行了表征,并以罗丹明B(RB)的脱色降解为模式反应,考察了材料的可见光催化性能.结果表明:γ-Bi2O3纳米片均匀地生长在TiO2纤维上,形成了具有异质结构的γ-Bi2O3/TiO2复合纤维光催化材料,其光谱响应范围拓宽至可见光区,有利于TiO2光生电子和空穴的分离,增强了体系的量子效率.与纯TiO2纤维相比可见光催化活性明显提高,对RB的脱色率达87.8%.     

玄武岩纤维/TiO2复合材料的制备及表征

TiO_2纳米粉体应用于光催化领域存在光吸收仅局限于紫外光区域、难以回收等缺点,因此,纳米TiO_2固定化和可见光改性成为光催化领域的两个研究热点.本文采用绿色环保的水热法,将TiO_2负载于玄武岩纤维载体上,在较低的温度下制备出一种新型的玄武岩纤维/TiO_2复合材料.使用XRD分析了复合材料的物相结构,采用SEM观测了复合材料的形貌,并对水热法合成其机理进行了分析.结果表明:150℃水热条件下、反应10 h合成的玄武岩纤维/TiO_2复合材料中,颗粒状的TiO_2涂层均匀包覆于玄武岩纤维表面,并没有改变玄武岩纤维结构,形成了一种具有核壳结构的新型玄武岩纤维/TiO_2复合材料,经过TiO_2修饰的玄武岩纤维对可见光有很好吸收.因此,玄武岩纤维/TiO_2复合材料是一种具有潜在应用价值的可见光催化材料.     

Preparation and characterization of composite fibers from organic-soluble chitosan and poly-vinylpyrrolidone by electrospinning

Ultrafine composite fibers were fabricated by electrospinning of chloroform solutions of organic-soluble chitosan (O-CS) and poly-vinylpyrrolidone (PVP). The composite fibers were subjected to detailed analysis by Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The FT-IR showed that the composite fibers contained the two polymers. The SEM image results confirmed that the morphology and diameter of the fibers were remarkably affected by the process and the parameters of the electrospinning. The governing parameters included the applied voltage, the viscosity of the electrospun solution and tip-to-collector distance, and were further investigated.     

Cu/ n2TiO 2/ PBO复合纤维的制备

以 PBO纤维为基体 , 采用浸渍涂覆法在 PBO纤维表面包覆纳米 TiO 2膜 , 采用化学镀法将 Cu沉积到纳米 TiO 2膜表面 , 制备了 Cu/ n2 TiO 2/ PBO复合纤维 , 研究了影响纳米 TiO 2沉积速率和 Cu 沉积速率的主要因素。结果表明 , 纳米 TiO 2与偶联剂的浓度配比是影响纳米 TiO 2包膜形成的主要因素 , 当纳米 TiO 2与偶联剂浓度配比为 1∶1. 2时 , 制备的 n2TiO 2/ PBO复合纤维界面结合力较好 , 且纳米 TiO 2包覆层比较均匀。影响化学镀铜- 1 的主要因素有镀液成分、 反应时间和反应温度。在镀液成分的浓度配比为 CuSO 4·5H 2O 12 g ·L 、KNaC 4H 4 - 1 - 1 - 1O 68 g·L 、HCHO 6 mL ·L 和 NaOH 10 g·L , 反应温度 50℃, 镀铜时间 20 min的条件下 , 制备了负载均匀 , 界面结合力较好的 Cu/ n2 TiO 2/ PBO复合纤维。     

Synthesis of ultrafine lanthanum ferrite (LaFeO3) fibers via electrospinning

Ultrafine one-dimensional LaFeO₃ nanofibers were synthesized by electrospinning utilizing sol-gel precursors. The surface morphology, microstructure and crystal structure were investigated by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The nanofibers with smaller diameter were continuous and uniformly distributed. Typical fiber diameter was between 180 nm and 220 nm and the average diameter was 200 nm. The fibers consisted of many single-crystal LaFeO₃ grains and the grain size was about 20-50 nm. The relationship between the diameter of as-synthesized fibers and the PVP concentration of the precursor was investigated. The experimental results indicated that the PVP concentration had a great impact on the fiber size and 5.89 wt.% PVP concentration in sol-gel precursors was advantageous to the formation of more uniform electrospun composite fibers with smaller diameter.