二氧化钛纳米管的微波合成及其表征

本文采用微波法快速合成了锐钛矿型Ti O2纳米管,并用FT-IR、XRD、TEM等测试技术对其结构和形貌进行了表征。结果表明,采用该方法制得的Ti O2纳米管尺寸均一、形貌均匀整齐;同时对其研究过程中存在的问题以及其今后发展方向进行了展望。     

聚苯胺低维纳米结构的研究现状

综述了聚苯胺低维纳米结构在制备方法、形成机理以及功能特性等方面的研究现状。重点阐述了聚苯胺纳米管、纳米纤维的制备方法,包括模板法、界面法、自组装法、电化学法等,同时简要介绍了聚苯胺纳米管、纳米纤维的生长机理,展望了其在生物传感器、纳米电子器件、电致变色材料、复合材料等方面的应用前景。总结了聚苯胺低维纳米结构方面的最新研究进展,如聚苯胺纳米空心球、网状结构、菊花状结构、螺旋结构以及聚苯胺薄膜等的制备方法及特性,展望了其潜在的应用领域和广阔的发展前景。     

AAO模板合成低维有序纳米结构材料的研究进展

阳极氧化铝(AAO)模板因其独特的结构成为合成纳米线、纳米管等低维有序纳米材料的重要工具。综述了阳极氧化铝(AAO)模板的制备及其采用各种沉积方式合成低维有序纳米结构材料的最新研究进展,包括电化学沉积、化学气相沉积、sol–gel法和化学镀,指出了目前研究中需要解决的关键问题。     

原子层沉积Al_2O_3纳米管弯曲模量的原位研究

本文使用原子层沉积技术以及模板法制备了厚度、成分和结构精确可控的氧化铝纳米管,结合SEM、TEM、SAED和XPS分析,可知所得为非晶态氧化铝纳米管状结构且薄膜致密无针孔,沉积速率为0.11 nm/cycle,实现了纳米管壁厚在纳米尺度精确可控制备。进一步使用自主设计的SEM/SPM(扫描电子显微镜/扫描探针显微镜)联合测试系统,对氧化铝纳米管进行了原位三点弯曲实验研究。结果表明外半径在50 nm左右的氧化铝纳米管的杨氏模量范围在400~600 GPa之间,且杨氏模量值随着纳米管壁厚的增大而递减。     

二氧化钛纳米管光催化剂的制备及性能

以自制TiO_2纳米粉体为前驱体,NaOH溶液为水热介质,采用常压水热法制备了TiO_2纳米管光催化剂,利用X-射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)等分析手段对样品进行了表征。运用定性抑菌圈法考察了TiO_2纳米管对金黄色葡萄球菌和枯草杆菌的抑菌性能,并测定了其对甲基橙溶液的光催化降解活性。结果表明,采用该方法得到的TiO_2纳米管为锐钛矿相,结构清晰、管形均匀,对两种细菌表现出了良好的抑菌性能,其光催化降解率在光照90 min时达到84.840%。     

硅纳米管的水热法合成与表征

采用水热法成功合成了新型的硅纳米管一维纳米材料,并采用透射电子显微镜、选区电子衍射分析、能量色散光谱及高分辨透射电子显微镜对合成的硅纳米管进行了表征.研究表明硅纳米管是一种多壁纳米管,为立方金刚石结构,生长顶端呈半圆形的闭合结构,由内部为数纳米的中空结构,中部为晶面间距约0.31nm的晶体硅壁层,最外层为低于2nm的无定形二氧化硅等三部分组成.     

硅纳米管的水热法合成与表征

采用水热法成功合成了新型的硅纳米管一维纳米材料,并采用透射电子显微镜、选区电子衍射分析、能量色散光谱及高分辨透射电子显微镜对合成的硅纳米管进行了表征．研究表明硅纳米管是一种多壁纳米管,为立方金刚石结构,生长顶端呈半圆形的闭合结构,由内部为数纳米的中空结构,中部为晶面间距约0.31nm的晶体硅壁层,最外层为低于2nm的无定形二氧化硅等三部分组成．     

电泳法制备TiO_2纳米阵列及其杂化太阳电池

采用溶胶-凝胶电泳法,以在氧化铟锡(ITO)导电玻璃基底上的多孔阳极Al2O3膜为模板,通过改变TiO2前驱体溶胶的陈化时间,制得TiO2纳米棒与纳米管阵列。通过扫描电镜、X射线衍射仪和电沉积I-t曲线对纳米棒和纳米管阵列进行了分析,阐述了纳米棒和纳米管的生长机理,解释了纳米棒和纳米管之间的转变是纳米结构生长速度与带电胶体粒子迁移速度相互竞争的结果。利用TiO2纳米棒和纳米管阵列与聚3-己基噻吩(P3HT)组装成杂化太阳电池,发现纳米阵列结构太阳电池相比其他结构的太阳电池效率更高;而纳米管阵列太阳电池比纳米棒阵列太阳电池性能更优,这得益于其更大的比表面积,可以承载更多的聚合物,并提供更大的分离界面。     

一维AlN纳米结构制备进展

采用CVD、碳纳米管模板法等方法已经制成了纳米线、纳米管等多种结构;同时研制成功多种一维纳米结构的阵列。用CVD方法合成的AlN纳米线直径为几十纳米、纳米线长度可以达到几十微米;用碳纳米管模板法可以控制AlN纳米线的直径。同时,AlN纳米线也已经在场致发射的研究领域得到应用。综述了AlN一维纳米结构材料的制备方法,分析研究了AlN一维纳米结构的合成反应机理和材料特性。     

TiO_2纳米管阵列对染料敏化太阳能电池性能的影响

通过恒压阳极氧化法在Ti箔表面制备了结构规整的TiO2纳米管阵列,研究了氧化时间和退火温度对纳米管阵列的尺寸和晶体结构的影响。用制得的纳米管阵列电极组装了染料敏化太阳能电池(DSSC),研究了纳米管长度、退火温度和电极面积对DSSC光电性能的影响。结果表明,纳米管管径和壁厚均与氧化时间无关,而纳米管长度则随着氧化时间延长而增加。在450℃及更低温度退火时,纳米管中只出现锐钛矿相;而在500℃退火时,纳米管中则又出现了金红石相。由厚度为27μm、退火温度为450℃的纳米管阵列电极组装成的DSCC具有最佳的光电转化性能。DSCC的光电转化效率随电极面积的增加而降低。     

MoxWx–1S2 Nanotubes for Advanced Field Emission Application

Transition metal dichalcogenide (TMDC) nanotubes complement the field of low-dimensional materials with their quasi-1D morphology and a wide set of intriguing properties. By introducing different transition metals into the crystal structure, their properties can be tailored for specific purpose and applications. Herein, the characterization and a subsequent preparation of single-nanotube field emission devices of Mo_xW_x-1S₂ nanotubes prepared via the chemical vapor transport reaction is presented. Energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray diffraction  indicate that the molybdenum and tungsten atoms are randomly distributed within the crystal structure and that the material is highly crystalline. High resolution transmission electron microscopy  and electron diffraction (ED) patterns further corroborate these findings. A detailed analysis of the ED patterns from an eight-layer nanotube reveal that the nanotubes grow in the 2H structure, with each shell consists of one bilayer. The work function of the nanotubes is comparable to that of pure MoS₂ and lower of pure WS₂ NTs, making them ideal candidates for field emission applications. Two devices with different geometrical setup are prepared and tested as field emitters, showing promising results for single nanotube field emission applications.     

A diameter-selective chiral separation of single-wall carbon nanotubes using nitronium lons

We propose a method for a diameter-selective removal of metallic single-walled carbon nanotubes (m-SWCNTs) from semiconducting (s-) ones. Our separation technique is capable of 100% separation of semiconducting and metallic nanotubes for small diameter nanotubes. We dispersed SWCNT powder by sonication in a mixed solution of tetramethylene sulfone and chloroform, where nitronium ions were well disolved. Positively charged nitronium ions were intercalated into nanotube bundles, where the intercalation was promoted also by the counter ions. Nitronium ions selectively attacked the sidewall of m-SWCNTs due to the abundant presence of electron density at the Fermi level, thus yielding stronger binding energy compared to the counterpart s-SWCNTs. The s-SWCNTs were left on the filter after filtration, whereas m-SWCNTs were perfectly destroyed by nitronium ions and drained away as amorphous carbons. This preferable adsorption became obscured for nanotubes with diameters greater than 1.1 nm. The effectiveness of removing m-SWCNTs was confirmed by the transmission electron microscope observations, x-ray photoemission spectra, resonant Raman spectra, and absorption spectra.     

High energy-resolution electron energy-loss spectroscopy study of the electric structure of double-walled carbon nanotubes

Electron energy-loss spectra were obtained from two double-walled carbon nanotubes (DWCNTs) with an energy resolution of 85 meV. The spectra showed multiple peak structures between 2 and 3 eV. However, peak positions are different for these two DWCNTs. The chiral indices of CNT layers of the two DWCNTs were determined to be (29,4)(in) (17,8)(out) and (46,6)(out) (26,21)(in), respectively, by comparing experimental electron diffraction patterns with simulated ones. The spectra were also compared with simulated joint density of states, which were derived from the determined chiral indices. It was confirmed that the peak structures in the spectra are due to interband transitions intrinsic for tubular structures of graphitic sheets.     

Tuning and Enhancing Photoluminescence of Light‐Emitting Polymer Nanotubes through Electron‐Beam Irradiation

A new method for the tuning and enhancing photoluminescence (PL) characteristics of light emitting poly (3‐methylthiopnehe) (P3MT) nanotubes through E‐beam irradiation under atmospheric environments is reported. An E‐beam generated from a linear electron accelerator (1 MeV, 1.6 × 10¹³–8.0 × 10¹⁶ electrons cm^–2) is irradiated onto P3MT nanotubes including an Al₂O₃ template. From laser confocal microscope (LCM) PL experiments, significant enhancements in the PL intensity—up to about 90 times of an isolated single strand of the E‐beam irradiated P3MT nanotubes—are observed. The luminescent color of the P3MT nanotubes changes from green to red color depending on the variation of E‐beam dosage. These results might originate from the de‐doping effect and the conformational modification through E‐beam irradiations. Conformational changes of the E‐beam irradiated P3MT nanotubes are confirmed by LCM single Raman and ultraviolet‐visible (UV/Vis) absorption spectra. From UV/Vis absorption spectra, it is observed that the π–π* transition peak and the doping induced bipolaron peaks of the P3MT nanotubes dramatically vary with E‐beam irradiating conditions.     

Hydrothermal Synthesis of Rare Earth (Tb,Y) Hydroxide and Oxide Nanotubes

In this paper, Tb(OH)₃ and Y(OH)₃ single‐crystalline nanotubes with outer diameters of 30–260 nm, inner diameters of 15–120 nm, and lengths of up to several micrometers were synthesized on a large scale by hydrothermal treatment of the corresponding oxides in the presence of alkali. In addition, Tb₄O₇ and Y₂O₃ nanotubes can be obtained by calcination of Tb(OH)₃ and Y(OH)₃ nanotubes at 450 °C. X‐ray diffraction (XRD), field‐emission scanning electron microscopy, transmission electron microscopy (TEM), electron diffraction (ED), energy‐dispersive X‐ray spectroscopy (EDS), thermogravimetry, and differential scanning calorimetry (DSC) have been employed to characterize these nanotube materials. The growth mechanism of rare earth hydroxide nanotubes can be explained well by the highly anisotropic crystal structure of rare earth hydroxides. These new types of rare earth compound nanotubes with open ends have uses in a variety of promising applications such as luminescent devices, magnets, catalysts, and other functional materials. Advantages of this method for easily realizing large‐scale production include that it is a simple and unique one‐pot synthetic process without the need for a catalysts or template, is low cost, has high yield, and the raw materials are readily available. The present study has enlarged the family of nanotubes available, and offers a possible new, general route to one‐dimensional single‐crystalline nanotubes of other materials.     

Li-inserted carbon nanotube Raman scattering

The possibility of inserting lithium into single wall carbon nanotube bundles during the growth process is analyzed in this work by using the Raman technique as probe. The nanotubes were prepared by the arc discharge method by using catalysts prepared by mixing compounds containing lithium and as their counterpart, a similar mixture without this alkali-metal. The two pair of samples studied in this work were obtained with the following catalysts: (i) Li₂CO₃/NiO/CoO and NiO/CoO; or (ii) LiCo_0.5Ni_0.5O₂ and Ni/Co. Raman spectra reveal that the tangential bands profiles of the samples prepared with the catalyst containing lithium is considerably modified in both cases. In the case of the carbon nanotubes obtained using the LiCo_0.5Ni_0.5O₂ catalyst a down shift and severe broadening are observed in addition. Comparison of our results with those published previously for alkali-metals doped single wall carbon nanotubes allowed to conclude that lithium incorporation, actually, occurs during the growth process.     

Relation between peak structures of loss functions of single double-walled carbon nanotubes and interband transition energies

Electron energy-loss spectra of single double-walled carbon nanotubes (DWCNTs) were compared with calculated joint density of states (jDOSs) obtained by a simple tight-binding (STB) and an extended tight-binding (ETB) method. From the comparisons, interband transition energies of ETB calculations show better agreement with peak positions of the experimental spectra than those of STB results. From a further comparison among calculated jDOS, real and imaginary parts of a dielectric function and a loss function Im[-1/epsilon], it was confirmed that the peak energies in a spectrum of single DWCNTs are almost equal to those of the optical absorption spectrum epsilon(2).     

ZnO纳米管的制备及光学特性研究

ZnO nanotubes have been fabricated through a carbon thermal reduction deposition process. Structure characterization results show that the ZnO nanotubes have a single crystalline wurtzite hexagonal structure pref- erentially oriented in the c-axis. The diameters of ZnO nanotubes are in the range of 90-280 nm and the wall thickness is about 50-100 nm. Room-temperature photoluminescence measurements of the ZnO nanotubes exhibit an intensive ultraviolet peak at 377 nm and a broad peak centered at about 517 nm. The UV emission is caused by the near band edge emission while the green emission may be attributed to both oxygen vacancy and the surface state. Raman and cathodoluminescence spectra are also discussed. Finally, a possible growth mechanism of the ZnO nanotubes is proposed.     

Effect of SWNT Defects on the Electron Transfer Properties in P3HT/SWNT Hybrid Materials

Poly(3‐hexylthiophene) (P3HT) hybrids with single‐walled carbon nanotubes (SWNTs) were prepared using a series of SWNTs with various defect contents on their surfaces. The hybrids were synthesized by exploiting the π–π interaction between P3HT and the SWNTs, resulting in efficient dispersion of the carbon nanotubes in the P3HT solution. UV‐visible and photoluminescence (PL) spectra showed that the carbon nanotubes quench the PL of P3HT in the hybrids, indicating that electron transfer occurs from photo‐excited P3HT to the SWNTs. This electron transfer from P3HT to carbon nanotubes was disrupted by the presence of defects on the SWNT surfaces. However, the PL lifetime of P3HT in the hybrids was found to be the same as that of pure P3HT in solution, indicating the formation of a ground‐state non‐fluorescent complex of P3HT/SWNTs.     

碳纳米管电极上的电化学行为分析

用化学方法对碳纳米管进行表面处理 ,用红外谱对处理后的碳纳米管进行表征 ,处理后的碳纳米管表面出现了活性功能团羧基。用这些碳纳米管制成电极 ,对Cd离子在硫酸钠中的电化学行为进行了分析。结果表明 ,从碳纳米管电极上可以观察到很好的、准可逆循环伏安图 ;在扫描速度为 10 0mV·s- 1时 ,氧化还原峰电位分别出现在 - 0 .6 5V和 - 0 .95V对照饱和甘汞电极(SCE)。峰电流与扫描速度的平方根成良好的线性关系 ,说明反应过程是由镉离子的扩散控制的。由循环伏安图相关的电位与扫描速度关系 ,我们导出了电子转移动力学速度参数。由于碳纳米管电极有很好的电化学活性和可重复性 ,它可以成为一种新型的分析电极材料