熔融法制备纳米管Li-Ti-O化合物及其表征

在熔融的LiNO₃中，以纳米管钛酸钠为母体进行锂-钠离子交换，制得了具有高表面积的纳米管Li-Ti-O化合物(198.6 m²·g^-1)。XRD、XPS、TG表征结果表明: 此纳米管Li-Ti-O化合物包含两种晶型物质, 即立方尖晶石结构的Li₂Ti₂O₄和锐钛矿结构的Li_xTiO₂(x＜0.1)]，Li⁺在这两种晶型物质中的结合能不同；在空气中此纳米管Li-Ti-O化合物具有较强的吸水性，化学吸附水在高于400 ℃时才开始脱附。     

纳米ZnO的制备及发光特性研究

The samples of nano-size ZnO were prepared by precipitation, hydrolysis, sol-gel method and characterized by X-ray diffraction, Uv-Vis diffuse reflection spectrum, and time resolved luminescent spectrum. The results showed that the crystallite dimensions of all ZnO samples were coarsening with increasing annealing temperature and the grain sizes prepared by sol-gel method were obviously smaller than the others prepared by precipitation and hy-drolysis method. Under excitation of monochromatic light of wavelength 300nm, a strong and broad photolumines-cence (PL) emissions were observed in the wavelength range of 420～780nm. As the grain size decreased, the PL peak positions moved to shorter wavelengths. And as the annealing temperature increased, the peak intensity de-creased. The photoluminescence decay profile of ZnO was well described by three decay components of 46ns, 330ns and 1630ns.     

自组装金属有机纳米管模板法制备高分子纳米管

高分子纳米管(PNT)是一类具有中空管状结构的高分子纳米材料, 模板法是制备管状高分子纳米材料的有效方法. 本研究以自组装金属有机纳米管(MONT)为模板, 杈状多元胺和多元羧酸为前体分子, 利用杈状多元胺与MONT表面的铜离子配位络合, 在MONT表面上形成包覆层, 再与同样具有杈状结构的多元羧酸活化酯进行交联反应后, 去除掉内部的自组装模板, 从而制得具有良好水分散性的PNT. 利用扫描电子显微镜(SEM)、扫描透射电子显微镜(STEM)、差示扫描量热仪(DSC)、X射线衍射(XRD)和漫反射傅立叶变换红外光谱(DRIFTS)对PNT的表面形貌、组成和结构进行了表征. 结果表明, 当多元胺用量为MONT用量的0.4摩尔当量时, 交联产物的成管率最高, 达80%以上, 纳米管的长度大多为500 nm~3 μm、内径为60~100 nm、外径80~120 nm.     

钛酸纳米管的化学修饰及发光性能的稳定化

钛酸纳米管表面富有羟基, 利用十六醇与Ti-OH发生脱水反应对钛酸纳米管进行化学修饰. 通过透射电子显微镜、红外光谱和荧光光谱等方法研究了表面修饰对钛酸纳米管的结构及光学性质的影响. 与未修饰的钛酸纳米管相比, 不溶于有机溶剂的钛酸纳米管修饰后溶于氯仿、甲苯中, 为进一步用LB膜技术组装钛酸纳米管提供了条件, 并且钛酸纳米管表面修饰的有机层有效抑制了纳米管表面对水的吸附, 解决了钛酸纳米管在空气中久置或有水气氛下特殊的可见区吸收和荧光发光现象受到影响的问题, 使钛酸纳米管的发光性质稳定, 为钛酸纳米管的广泛应用奠定了基础.     

非晶态合金纳米管的制备及其催化性能研究进展

 在 Tween 系列非离子/阴离子混合型表面活性剂与过渡金属盐所形成的溶致液晶体系中加入 NaBH4, 制备了过渡金属 (M) 与 B 的非晶态合金纳米管 M-B (M = Fe, Co, Ni); 制备时若在含 Ni 盐溶液中添加第三种组分 (可为 P, Co 或 Cu 的化合物), 则还可得到相应的 NiPB, NiCoB 或 NiCuB 三元非晶态合金纳米管. 讨论了这类反应的机制, 指出层状液晶相模板的存在是获得纳米管的关键, 层中过渡金属离子被 NaBH4 还原的同时析出 H2, 导致层状液晶相解离并卷曲形成纳米管. 在这一基础上通过微调实验条件并添加适当的稳定剂, 可得到稳定的二元或三元过渡金属非晶态合金纳米管, 并可在一定范围内调控其管径. 在某些加氢反应中, 非晶态纳米管具有比相应的非晶态纳米颗粒更好的催化性能, 而且管径小的纳米管的催化性能比管径大的更好. 由于非晶具有与结晶材料迥异的特性, 非晶态合金纳米管可能具有独特的性能和应用前景.     

载Ag二氧化钛纳米管的制备及其光催化性能

Titania nanotubes (TNTs) were synthesized by hydrothermal treatment of rutile-phase TiO2 nanoparticles in 10 mol·L-1NaOHsolution at 110 ℃ for 24 h. The Ag loaded titania nanotubes (Ag/TNTs) were obtained by chemical deposition method with the TNTs suspending in the AgNO3 solution (pH=8) at 50 益. The characterizations of the as-synthesized samples were performed by TEM, EDS, XRD, XPS, and UV-Vis spectra. The photocatalytic performance of the Ag/TNTs was investigated by UV-light induced photocatalytic decomposition of methyl orange(MO). The results showed that the inner/outer diameters of TNTs were about 6/10 nm and the length was several hundred nanometers. Both the shape and the crystalline of the nanotubes were not changed after the modification. The zero oxidation state Ag quantumdots, about 4 nmin diameter, were well dispersed on the external surface of the nanotubes. Ag/TNTs exhibited enhanced absorption at the visible range in the UV-Vis spectra. The Ag nanoparticles were found to significantly enhance the photocatalytic activity of TiO2 nanotubes, and the catalyst system was demonstrated to be highly efficient for the UV-light induced photocatalytic decomposition of MO compared to both rutile-phase TiO2 nanoparticles and pure TNTs. After irradiation for 60 min, the decomposition rates of MO solution in rutile-phase TiO2 nanoparticles, TNTs, and Ag/TNTs systemwere 46.8%, 57.2%, and 92.2%, respectively.     

镶嵌CdS的纳米管钛酸制备及其光催化性能研究

制备了镶嵌硫化镉的纳米管钛酸,并用透射电镜(TEM)、X射线衍射(XRD)、扩散反射(DRS)等工具进行了表征.丙烯的光催化氧化研究结果表明,镶有CdS与未镶CdS的纳米管钛酸作为光催化剂,对丙烯的光催化去除活性相近.     

碳化硅纳米管的制备及表征

Silicon carbide nanotubes (SiCNTs) were prepared by chemical vapor deposition (CVD). Methyltrichlorosilane (MTS) was selected as the SiC gaseous source and, ferrocence and thiophene as the catalyst and the cocatalyst, respectively. The influences of pyrolysis temperature, the content of catalyst and the cocatalyst, and the mole ratio between H₂ and MTS, on the shape of the pyrolysis products were investigated, respectively. The products were characterized by SEM, EDX, XRD and HRTEM, respectively. Novel type of multi-walled SiCNTs, with 30～80 nm and 15～20 nm outer and inner diameters, respectively, were observed.     

CdS纳米管有序阵列的制备和表征

CdS is an important semiconductor material, and has received much attention. In this paper, we reported a sol-gel method for synthesis of CdS nanotube arrays which has not been reported yet. The products were charac-terized by SEM, TEM and EDS. The CdS nanotube is about 60μm in length, and about 100nm in diameter cor-responding to that of the alumina template. The further research is under way.     

聚合物微纳米管的制备技术

由于聚合物微纳米管独特的一维中空结构和性能多样性,在分离、电子器件、催化剂负载、药物释放等方面具有广泛的应用前景,本文结合最新的研究进展,总结了聚合物微纳米管的制备方法,并重点介绍了硬模板法、软模板法和无模板法的特点。     

Synthesis and Photoluminescence of Amorphous Silicon Oxycarbide Nanowires

Synthesis of amorphous SiCO nanowires was carried out by means of direct current arc discharge. Free-standing SiCO nanowires were deposited on the surface of a graphite crucible without any catalyst and template. The SiCO nanowires were analyzed by XRD, SEM, TEM, XPS, and FTIR. The SiCO nanowires were typically 20—100 μm in length and 10—100 nm in diameter as measured by SEM and TEM. The XPS and FTIR spectroscopy analysis confirmed that the Si atoms share bonds with O and C atoms in mixed SiCO units. The PL spectrum of the SiCO nanowires showed strong and stable white emissions at 454 and 540 nm. A plasma-assisted vapor-solid growth mechanism is proposed to be responsible for the formation of the SiCO nanowires.     

一种新型光致发光自愈合水凝胶的合成

采用自由基聚合法制备了具有光致发光特性的自愈合水凝胶, 解决了光致发光配合物在水相荧光猝灭的问题. 通过分子设计, 利用共价键将油溶性的含Eu稀土配合物引进水凝胶体系中, 发现该配合物在水凝胶体系中稳定存在, 不扩散. 含Eu稀土配合物具有紫外光致发光的特性, 赋予该水凝胶良好的可识别性. 同时该水凝胶含有动态硼酸酯键, 其快速愈合的特性使该水凝胶在受损后能短时间内修复损伤, 为制备可发光水凝胶和可识别生物医用材料提供了新的思路.     

Synthesis, Photoluminescence and Photocatalytic Performance of BiPO4 with Different Phase Structures

Three kinds of crystal phase BiPO₄(HP, LTBP, and HTBP) were selectively synthesized by controlling the preparation conditions. Structures of the three samples are all constructed by PO₄ and BiO₈ polyhedra but with different geometric structures. Detailed characterization was carried out by X-ray diffraction(XRD), scanning eletron microscopy(SEM) and Raman, UV-Vis, and luminescence spectrometries. Three samples exhibit huge distinctions in their photoluminescence(PL) lifetime: 0.68, 162 and 160 μs for HP, LTBP, and HTBP, respectively. More interesting, an outstanding photocatalytic activity is observed for as-prepared LTBP nanorod, which shows even higher activity for the degradation of MB solution than P25. In addition, experiments were carried out to clarify the role of hydroxyl (^·OH) and superoxide radicals(O₂^·) played in photocatalytic process and it was found O₂^· was the main active species in BiPO₄ photocatalysts. Further comparison of structural and photocatalytic properties of the three samples finds that structure distortion is contributed to their property difference. A correlation was found between photocatalytic performance and the distortion of BiO₈ dodecahedra. The internal field generated by the distortion of BiO₈ dodecahedra was believed advantageous for the separation of electron and hole, which was in favor of the improvement of photocatalytic activity. This correlation may help to design other photocatalysts with high activity.     

Zn_2SnO_4纳米材料制备及光致发光特性

以ZnO、SnO2和活性炭的混合物为原料,通过碳热还原热蒸发法无催化剂成功制备出Zn2SnO4纳米材料.借助X射线衍射仪(XRD)、拉曼光谱和扫描电子显微镜(SEM)对样品物相和形貌进行了表征,结果显示样品为面心立方结构的Zn2SnO4纳米链状棒,同时含有少量的ZnO物相.利用X射线光电子能谱(XPS)对Zn2SnO4样品表面各元素的化学状态及相互作用方式进行了测试,结果表明:样品中Zn和Sn分别是以+2价和+4价氧化态形式存在,其中Zn2p3/2电子有两个结合能,分别来自ZnO和Zn2SnO4,Zn2SnO4中Sn4+占据不同的格点位置.室温下光致发光谱(PL)结果显示,样品在紫外区域(320-450nm)和可见区域存在很强的发光带,其中紫外区域的宽发光带,经过高斯拟合可分为358和385nm两个发光峰,与同条件下制备得到的纯ZnO纳米材料发光谱比较,确认358nm发光峰是来自于Zn2SnO4的近带边复合发光.     

KMnF3晶体的简单溶液合成及发光特性研究

Pure complex fluorides of KMnF3 crystal of spherical plate with a diameter of about 300 nm were successfully prepared by a simple aqueous synthesis method at room temperature. The sample was characterized by X-ray diffractometer (XRD), transmission electron microscopy, and selected area electron diffraction. An XRD result proves that the product is KMnF3 of perovskite-structure. By TEM and SAED results, it is found that the spherical plate morphology of sample is formed by self organization of KMnF3 grains. The sample shows two strong emissions at 416 and 438 nm, some discussion is made about the photoluminescence spectra and the resource of the emissions, at the same time, with the formula: Eem=-16963+164R and the photoluminescence spectrum, the bond distance of Mn-F could be estimated. Based on the obtained data it is easy to know the crystal parameter of samples with the perovskite-structure by results of photoluminescence spectra.     

溶剂热法制备六角锥形ZnO及其光致发光性能

通过乙酸锌和醇溶液反应得到了六角锥形纳米ZnO颗粒, 反应过程中不使用碱溶液和表面活性剂. 利用透射电子显微镜(TEM)、选区电子衍射(SAED)及扫描电子显微镜(SEM)对其形貌和结构进行了表征分析. 结果表明, 此方法制备的ZnO颗粒为单晶, 而且六角锥形ZnO的室温光致发光谱(PL)在378 nm处显示出了单纯的紫外发射峰, 而不是通常报道的可见光区发射, 这也预示着这种特殊结构的纳米ZnO将会成为一种具有良好应用前景的光学材料.     

Photoluminescence properties of BaMoO4 amorphous thin films

BaMoO₄ amorphous and crystalline thin films were prepared from polymeric precursors. The BaMoO₄ was deposited onto Si wafers by means of the spinning technique. The structure and optical properties of the resulting films were characterized by FTIR reflectance spectra, X-ray diffraction (XRD), atomic force microscopy (AFM) and optical reflectance. The bond Mo-O present in BaMoO₄ was confirmed by FTIR reflectance spectra. XRD characterization showed that thin films heat-treated at 600 and 200 °C presented the scheelite-type crystalline phase and amorphous, respectively. AFM analyses showed a considerable variation in surface morphology by comparing samples heat-treated at 200 and 600 °C. The reflectivity spectra showed two bands, positioned at 3.38 and 4.37 eV that were attributed to the excitonic state of Ba²⁺ and electronic transitions within MoO²⁻₄, respectively. The optical band gaps of BaMoO₄ were 3.38 and 2.19 eV, for crystalline (600 °C/2 h) and amorphous (200 °C/8 h) films, respectively. The room-temperature luminescence spectra revealed an intense single-emission band in the visible region. The PL intensity of these materials was increased upon heat-treatment. The excellent optical properties observed for BaMoO₄ amorphous thin films suggested that this material is a highly promising candidate for photoluminescent applications.     

Hydrothermal Synthesis, Characterization and Photoluminescence Properties of GdOHCO3 Rhombic Microcrystals

GdOHCO₃ rhombic microcrystals were synthesized by hydrothermal method with urea used as the precipitator. Experimental parameters, such as the molar ratio of the starting reagents, reaction temperature and reaction time were examined. The as-obtained product was characterized by powder X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FTIR) and spectrofluorometry. The main reactions to form GdOHCO₃ were proposed. In addition, the photoluminescence(PL) properties of GdOHCO₃ rhombic microcrystals were discussed. The broad band located between 350 nm and 600 nm in the emission spectrum can be attributed to the self-trapped exciton luminescence.     

Synthesis of Single‐Walled Carbon Nanotubes in a High Frequency Furnace

An alternative method for the synthesis of single‐walled carbon nanotubes (SWCNTs) is presented, which is based on the co‐evaporation of a pure graphite body and a metal catalyst (nickel). The graphite body is inductively heated in a high frequency furnace up to ~2400 °C. Characterization of the produced soot was performed using SEM, TEM and Raman spectroscopy techniques.     

Nanotubes and nanowires

Synthesis and characterization of nanotubes and nanowires constitute an important part of nanoscience since these materials are essential building units for several devices. We have prepared aligned carbon nanotube bundles and Y-junction nanotubes by the pyrolysis of appropriate organic precursors. The aligned bundles are useful for field emission display while the Y-junction nanotubes are likely to be useful as nanochips since they exhibit diode properties at the junction. By making use of carbon nanotubes, nanowires of metals, metal oxides and GaN have been obtained. Both the oxide and GaN nanowires are single crystalline. Gold nanowires exhibit plasmon bands varying markedly with the aspect ratio. GaN nanowires show excellent photoluminescence characteristics. It has been possible to synthesise nanotubes and nanowires of metal chalcogenides by employing different strategies.