ZnO纳米锥光致发光性及印刷ZnO纳米锥场发射性能研究

利用物理热蒸发法制备大规模的蒲公英状的ZnO纳米锥,利用荧光光谱仪对ZnO纳米锥进行了光致发光性能测试.针对现有的丝网印刷碳纳米管(CNTs)薄膜需要各种后处理工艺后才能改善其场发射特性的问题,提出了一种不需任何后处理丝网印刷ZnO纳米锥的浆料配制工艺.用该工艺制备的丝网印刷ZnO纳米锥的场发射特性测试表明,ZnO纳米锥与制浆剂质量比为3∶5的薄膜的开启场强最低为2.25V/μm(电流密度为1μA/cm2),在4.6V/μm场强下,阳极荧光粉的发光点亮度高且分布均匀.说明该方法成本低,工艺简单,无需任何后处理,在ZnO纳米锥场发射显示器的制作中有很好的实际应用价值.     

一种提高碳纳米管场发射特性方法

针对碳纳米管场发射显示器亮度低、发光均匀性差的问题,提出了氧化锌掺杂的方法.通过将氧化锌(ZBO)颗粒和碳纳米管(CNTs)及其他有机物按比例配成浆料,丝网印刷制作了阴极试样.场发射特性研究结果表明:与具有同样印刷面积的普通CNT试样比较,掺杂试样的开启电场从1.70 V/μm降低到1.17 V/μm;在2.05 V/μm场强下发射电流从185μA上升到510μA.且掺杂氧化锌试样具有较好的发射稳定性和均匀性.通过微观表征和特性测试,初步推断场发射特性的提高的原因:由于混合掺杂试样中氧化锌地填充在碳纳米管之间或者覆盖在顶上,提高了膜层导电性,改善了发射体的热传导性,且增加了有效发射体密度.     

提高丝网印刷ZnO纳米针场发射均匀性稳定性

针对现有的ZnO纳米针场发射均匀性、稳定性不良的问题,本文提出丝网印刷碳纳米管(CNTs)掺杂过滤的ZnO纳米针的方法来提高其均匀性和稳定性.场发射特性测试表明,ZnO纳米针经过滤后可以提高场发射均匀性,CNTs的掺杂提高了印刷ZnO纳米针薄膜的场发射电流密度和稳定性,印刷CNTs掺杂的ZnO纳米针薄膜在烧结温度为450℃时,印刷ZnO纳米针薄膜的场发射电流密度较高.该方法在ZnO纳米针场发射显示器的制作中有很好的实际应用价值.     

电泳沉积碳纳米管的微波等离子体改性

采用电泳法在Si基底上沉积了碳纳米管(CNTs)薄膜, 并利用Ar微波等离子体对CNTs薄膜进行了改性处理, 研究了改性前后CNTs的微观结构和场发射性能. 高分辨透射电子显微镜(HRTEM)和拉曼光谱的表征结果表明, 等离子体改性明显改变了CNTs的微观结构, 形成了大量的管壁结构缺陷、纳米级突起和“针形”尖端; 场发射测试结果表明, CNTs经Ar等离子体改性处理后开启电场较改性前?略有增大, 等离子体改性10min的CNTs薄膜表现出最佳的场发射J-E特性, 阈值电场由改性前的3.12V/μm降低到2.54V/μm, 当电场强度为3.3V/μm时, 场发射电流密度由改性前的18.4mA/cm²增大到60.7mA/cm². 对Ar微波等离子体改性增强CNTs薄膜场发射性能的机理进行了分析.     

碳纳米管和镓掺杂碳纳米管场发射性能研究

采用催化热解方法分别 制备出碳纳米管和镓掺杂碳纳米管, 并利用丝网印刷工艺将其制备成纳米管薄膜. 对此薄膜进行低场致电子发射测试表明, 碳纳米管和镓掺杂纳米管开启电场分别为2.22和1.0V/μm, 当外加电场为2.4V/μm, 碳纳米管发射电流密度为400μA/cm², 镓掺杂纳米管发射电流密度为4000μA/cm². 可见镓掺杂碳纳米管的场发射性能优于同样条件下未掺杂时的碳纳米管. 对镓掺杂纳米管场发射机理进行了探讨.     

碳纳米管薄膜的低温制备及其场发射性能的研究

利用电镀方法在覆盖有金属Ti的玻璃衬底上制备了Ni催化剂,采用微波等离子体化学气相沉积技术,以CH4和H2为反应气体,在450℃的低温下制备了CNTs薄膜.利用扫描电子显微镜和Raman光谱对其表面形貌和结构进行了分析,在真空度小于2×10-4 Pa的环境中测试了CNTs薄膜的场致电子发射特性,开启电场2.7 V/μm.研究表明微波等离子体化学气相沉积技术低温制备CNTs薄膜是可行的,且该薄膜具有良好的场发射性能.     

高场发射性能碳纳米管薄膜的沉积与表征

利用电泳法将碳纳米管（CNTs）沉积在表面镀覆了50～150 nm Ti薄膜的Si基底表面,900℃真空退火后形成了具有良好场发射性能的Ti-CNTs薄膜阴极.利用X射线衍射和扫描电子显微镜对制备的Ti-CNTs薄膜进行了表征.结果表明,高温退火过程中,CNTs的C原子和基底表面的Ti原子发生化学反应,在CNTs与基底之间形成了导电性钛碳化物,明显改善了CNTs与基底之间的电导性和附着力等界面接触性能;与Si基底表面直接电泳沉积的CNTs薄膜相比,制备的Ti-CNTs薄膜的开启电场从1.31 V/μm降低到1.19 V/μm;当电场强度为2.50 V/μm时,Ti-CNTs薄膜的场发射电流密度可达13.91 mA/cm^2;制备的Ti-CNTs薄膜显示出改善的发射稳定性.     

碳纳米管/二氧化硅复合材料制备及场发射特性研究

采用溶胶-凝胶法制备了碳纳米管/二氧化硅复合材料,并对复合材料的场发射特性进行了研究,结果表明:复合材料有很好的场发射特性,含有10%(质量分数)CNTs的复合材料开启场较低(0.98V/μm).研究了用稀HF溶液处理复合材料表面后场发射性能,发现场发射性能明显改善,开启场由0.98V/μm下降到0.73V/μm,发射电流为1mA/cm2时的电场由2.1V/μm下降到1.0V/μm.研究表明碳纳米管/二氧化硅复合材料非常适用于场发射平面显示器中的阴极.     

ZnO纳米棒/CNTs复合阴极的制备及其场发射性能的研究

采用水热法和喷涂法制备ZnO纳米棒/CNTs复合材料,并测试其场发射性能。首先采用水热法在ITO电极基面生长ZnO纳米棒阵列,随后通过喷涂技术在ZnO纳米棒阵列表面沉积碳纳米管(CNTs)。使用扫描电子显微镜和X-射线衍射分别表征样品的结构和形貌特征。结果表明,经喷涂沉积的CNT薄膜均匀地包裹在ZnO纳米棒尖端。对该复合材料采用二极结构测试其场发射性能,通过测试结果发现,ZnO纳米棒/CNTs复合材料可明显改善ZnO纳米棒阵列及CNT薄膜的场发射性能,该复合材料具有低开启电场强度(约0.96V/μm),高场增强因子(9881)。因此,ZnO纳米棒/CNTs复合材料是最有前景的场发射阴极材料之一。     

碳纳米管薄膜的制备及其场发射研究

为了克服用Fe（NO3）3、Mg（NO3）2体系催化剂自由生长出的碳纳米管缠绕程度较严重,分布不均匀的缺点,采用丝网印刷催化剂的方法将其印刷在石英、硅和钛三种不同的基底上,结果表明,在石英基底上,用CVD法制备的碳纳米管分布较均匀,有效地克服了团聚现象,并用其作为场发射的阴极进行场发射实验,实验表明,该阴极开启场为2．2V／μm,在电场强度为3．0V／μm下,阳极电流为46．6uA,场发射电流稳定,波动小于5％。该阴极可望应用于场致发射显示器、液晶显示的背光源、照明光源等器件。     

Prevenient dye-degradation mechanisms using UV/TiO2/carbon nanotubes process

Photocatalysis research heavily emphasizes increasing photo-efficiency. This study presents the application of carbon nanotubes (CNTs) to increase the photocatalytic activity of TiO(2). It elucidates the effect of CNTs dose on the decolorization efficiency of aqueous azo dye, C.I. Reactive Red 2 (RR2), determines the effects of SO(4)(2-) formation and removal of total organic carbon (TOC), and measures the effects of various ultraviolet wavelengths. Scanning electron microscopy was used to elucidate the mixing phenomenon and the size of TiO(2) and CNTs; X-ray diffraction was used to determine crystallinity; a BET meter was used to measure surface area and a spectrophotometry was used to determine the decolorization of RR2. Experimental results indicated significant effects of photodegradation on the combination of TiO(2) with CNTs and electron transfer is higher for 410 nm irradiation than for 365 nm, revealing that solar light can be used. The electron transfer in the TiO(2)/CNTs composites reduced the electron/hole recombination and increased the photon efficiency and the prevenient dye-degradation mechanisms using UV/TiO(2)/CNTs were established.     

The fabrication of CNTs/TiO(2) photoanodes for sensitive determination of organic compounds

Titanium dioxide (TiO(2)) and carbon nanotubes (CNTs) are the two most popular functional materials in recent years. In this study, CNTs/TiO(2) composite and TiO(2) photoanodes were fabricated by a dip-coating technique, followed by subsequent calcination. The resultant photoanodes were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and UV-visible spectroscopy (UV-vis). The results suggest that the carbon nanotubes were successfully incorporated with the TiO(2) nanoparticulates without damage and that the resultant TiO(2) nanoparticles consisted of anatase and rutile. The CNTs/TiO(2) photoanodes were capable of oxidizing various types of organic compounds (e.g.?glucose, potassium hydrogen phthalate, and phenol) in aqueous solutions in a photoelectrochemical bulk cell. In comparison with the pure TiO(2) photoanode, the sensitivity of the photoanode for the detection of organic compounds has been improved by 64%, while the background current was reduced by 80% due to the introduction of the CNTs. These advantages can be ascribed to the improved adsorptivity to organic compounds, increased absorption of UV light and enhanced electron transport at the CNTs/TiO(2) photoanode due to the introduction of the CNTs.     

流化床化学气相沉积法制备CNT/Fe-Ni/TiO2及其光催化性能研究

以Fe-Ni/TiO2为催化剂,采用流化床化学气相沉积法(FBCVD)在TiO2表面原位生长碳纳米管(CNT),得到CNT/Fe-Ni/TiO2复合光催化剂.通过SEM、XRD、UV-Vis等方法表征其结构和性能,以亚甲基蓝溶液降解为模型考察其光催化性能.结果表明:Fe-Ni/TiO2催化剂在FBCVD过程中,镍主要起到了CNT生长催化活性位的作用;在生长CNT后的复合光催化剂中,比例较低的Fe3+主要作为电子俘获剂,抑制TiO2光生电子空穴的复合;Ni和CNT共同起到将电子迅速地从TiO2中导出,从而降低光生电子空穴复合几率的作用.三者的协同作用显著改善了TiO2的光催化性能.其中Fe和Ni掺杂量分别为0.25mol%和4.75mol%样品的光催化活性较高,生长CNT后得到的复合光催化剂对亚甲基蓝的降解效率较纯TiO2提高约70%.     

Ce-Ti-O_x/CNTs复合粒子的制备及其对风化煤氧解的催化性能

以柠檬酸为螯合剂,以自制碳纳米管(CNTs)为载体,采用柠檬酸螯合沉积法制备了Ce-Ti-Ox/CNTs复合粒子,考察了柠檬酸的用量和乙二醇的添加对产物形貌的影响,采用TEM、XRD和FR-IR等手段对样品的形貌和晶相结构进行表征。结果表明,乙二醇的"桥接"作用有效地改善了负载效果及被负载的粒子均匀。探讨了复合金属氧化物的负载机理,并在此基础上研究了所得样品在风化煤硝酸氧解制备腐植酸中的催化性能,催化结果表明,Ce-Ti-Ox/CNTs复合粒子的催化性能明显优于单纯的CNTs、CeO2、TiO2、CeO2/CNTs以及TiO2/CNTs的催化性能,使腐殖酸的产率达到了65.43%。     

氮掺杂改性TiO_2多孔薄膜光催化降解4-硝基苯酚

本文采用溶胶-凝胶法制备了N掺杂TiO_2光催化剂,并对N掺杂TiO_2进行了改性,分别以P25、N掺杂TiO_2、改性的N掺杂TiO_2为原料,通过逐步研磨、旋转涂膜以及高温煅烧制得三种多孔薄膜,并对其进行了表征。场发射扫描电子显微镜(FESEM)观察结果显示,煅烧后薄膜呈现显著的多孔结构。以4-硝基苯酚(4-NP)溶液为目标污染物,研究紫外光下TiO_2多孔薄膜的光催化性能,确定最佳降解条件,并研究了薄膜耐用性以及三种薄膜对4-NP的光催化性能的比较。结果表明,三种多孔薄膜中,改性N掺杂TiO_2多孔薄膜光催化性能最佳,10mg/L的4-NP溶液吸附30min,在pH=2条件下180min,降解率达到了90%以上,改性N掺杂TiO_2多孔薄膜单次降解180min,循环使用4次的降解率仍接近80%,显示了薄膜具有较好的可耐用性。     

Fabrication of dye-sensitized solar cell (DSSC) using different particle sizes of TiO2 deposited via nano-particle deposition system (NPDS)

TiO2 layers were fabricated using a nano-particle deposition system (NPDS) on transparent conductive oxide (TCO) glass for dye sensitized solar cells (DSSCs). Conventionally, TiO2 paste for working electrodes has been fabricated using paste type methods. The fabricated paste composed of a mixture of nano-sized TiO2 powders, binders and solutions is then painted on TCO glass. After drying, the TiO2 layer on TCO glass is sintered to make a path for electron transfer. TiO2 layers formed by this paste type method require numerous steps, which can be time consuming. In this study, TiO2 powders were sprayed directly on TCO glass using NPDS in order to simplify the fabrication steps. To improve porosity and produce scattering layers, commercial nanocrystalline TiO, powders with different sizes were alternately deposited. Moreover, powders with different sizes were mixed and deposited on the TCO glass. The results indicate that the DSSCs with a TiO2 layer composed of different particle sizes had better cell performance than the cells assembled with single-sized TiO2 particles. Therefore, this study shows that a dry TiO2 coating process is possible for DSSC fabrication to improve its cell efficiencies, and this method can easily be applied on flexible substrates since NPDS is a room-temperature deposition process.     

负载型催化剂对风化煤制备腐植酸的影响

以自制碳纳米管(CNTs)为载体,制备了负载型催化剂CeO2/CNTs、TiO2/CNTs和Ce-Ti-Ox/CNTs,并进行了TEM及XRD表征。以所得样品为催化剂用于东都风化煤降解制备腐植酸的研究,探讨了催化剂用量、反应温度及不同负载型催化剂对风化煤降解制备腐植酸的产率、分子结构及吸光度的影响。结果表明,所用负载型催化剂催化性能明显高于未负载的催化剂,能显著提高腐植酸的产率,而且所得腐植酸分子量较小,吸光度较高,其中Ce-Ti-Ox/CNTs催化效果最为显著,可使腐植酸的产率提高到65.43%,表明铈钛活性组分表现出了协同催化效应。     

Ag-CNT/TiO_2复合电极对亚甲基蓝的光电催化降解作用(英文)

采用金属银修饰的碳纳米管制备了Ag-CNT/TiO2复合电极。利用X-射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM),和能量分散性X射线分析(EDX)对所制的Ag-CNT/TiO2复合材料进行了表征。结果表明:二氧化钛颗粒和金属银颗粒在碳纳米管上均匀分布,所制电极具有较高的光电催化性能。其对亚甲基蓝的光电催化降解归因于一种协同效应,即二氧化钛的光降解、碳纳米管网络的电子辅助、金属银的增强和外加电势的作用。尤其是,经银修饰的复合电极增强了其对亚甲基蓝的光电降解,且随银含量的增加其光电催化效果增加。     

Self-standing crystalline TiO2 nanotubes/CNTs heterojunction membrane: synthesis and characterization

In the present study, we report for the first time synthesis of TiO(2) nanotubes/CNTs heterojunction membrane. Chemical vapor deposition (CVD) of CNTs at 650 °C in a mixture of H(2)/He atmosphere led to in situ detachment of the anodically fabricated TiO(2) nanotube layers from the Ti substrate underneath. Morphological and structural evolution of TiO(2) nanotubes after CNTs deposition were investigated by field- emission scanning electron microscopy (FESEM), glancing angle X-ray diffraction (GAXRD), and X-ray photoelectron spectroscopy (XPS) analyses.     

Enhanced electron transfer rate for quantum dot sensitized solar cell based on CNT-TiO2 film

In this paper, we have fabricated a quantum dot sensitized solar cell (QDSSC) based on carbon nanotube (CNT) doped TiO2 mesopores film. As revealed by field emission scanning electron microscopy and absorption spectra, the CdSe QDs were adsorbed onto CNT-TiO2 nanocomposite. An improved efficiency is achieved for the CNT-TiO2/CdSe devices compared to that of TiO2/CdSe, which is due to the increased surface area and reduced charge recombination in TiO2 film by the presence of CNTs. A power conversion efficiency of the as-prepared QDSSC of 0.98% was obtained under 100 mW/cm2 solar irradiation. The emission decay profile demonstrates that the electrons transfer from CdSe QDs to CNT-TiO2 is faster than that from CdSe QDs to TiO2, resulting in the reduction of the charge recombination, leading to a higher FF value in QDSSC. The average lifetime of CdSe QDs adsorbed on TiO2 doped with CNT is 6.2 ns and the electron transfer rate constant of 1.1 x 10(8) s(-1) can be calculated.