用于制备优质单壁碳纳米管管束的MgO负载Fe3O4纳米粒子的合成

采用沉淀方法制备了直径分布狭窄的均匀Fe3O4纳米颗粒.Fe3O4纳粒形体几近一致,平均粒径为10.33 nm±2.99 nm(平均粒径±标准偏差).在超声作用下将MgO纳米颗粒分散在一定量Fe3O4纳米颗粒的水溶液中获得MgO负载Fe3O4的纳米颗粒.以甲烷为碳源,Fe3O4/MgO为催化剂,经化学气相沉积,在Fe3O4纳粒上制得了大量直径近乎均匀的单壁碳纳米管(SWCNTs)束.TEM显示:SWCNTs的平均直径1.22rm.热重分析显示:样品在400℃～600℃温度区间失重量约19％.拉曼光谱显示:SWCNTs的ID/IG的强度比为0.03,表明采用Fe3O4/MgO催化剂可制得高石墨化程度的单壁碳纳米管.     

13X分子筛为载体制备单壁碳纳米管研究

采用流化床法,以Fe/13X分子筛作为催化剂载体,催化裂解正己烷制备出定向排列的、较纯的单壁碳纳米管.利用TEM、HRTEM、TG和Raman对产物进行了表征,对不同浸泡时间Fe/13X分子筛制成的单壁碳管的含量和分子筛的负载量进行了分析,研究了催化剂铁负载量对单壁碳纳米管的产量和直径的影响.结果表明,单壁碳纳米管产量受催化剂含量和活性的共同影响,且在一个特定催化剂负载量下碳管产量可以达到最高,而其直径变化不大,且不受催化剂负载量的影响.     

单壁碳纳米管作支撑的杂化金纳米催化剂比TiO_2和炭黑具有更优氧化芳香醇的性能（英文）

采用原位还原技术制备出以单壁碳纳米管、炭黑(P90)和TiO_2为支撑的3种金纳米复合材料,并通过多种表征手段来探讨物理性能。再将他们作为1-苯基乙醇、2-苯基乙醇和苯甲醇的绿色需氧氧化杂化催化剂来测试稳定性。在所有反应中,与P90和TiO_2相比,以单壁碳纳米管作支撑的金纳米杂化催化剂呈现出最优的反应效率和特异性。这些金纳米杂化催化剂经多次反应循环后反应活性衰减很小,从而能被重复使用。同时探讨了金纳米杂化催化剂活性高的原因,包括颗粒形貌、尺寸和支撑体性能。可以推断,基底上功能团迁移的位置、支撑材料的性质和活性金纳米颗粒相的颗粒尺寸分布均有助于使这些催化剂在反应中显示出高的选择性。     

碳纳米管/纳米铁颗粒杂化结构的制备及形成机理

采用催化化学气相沉积法将由C包覆的纳米铁颗粒(FeNP)原位沉积于碳纳米管(CNTs)表面并形成不同形貌的碳纳米管/纳米铁颗粒(CNTs/FeNP)杂化结构。使用扫描电子显微镜、透射电子显微镜对制备的杂化结构进行微观形貌分析和结构表征。结果显示,纳米铁颗粒通过石墨片层结构与碳纳米管相连,具有良好的界面结合。当噻吩的添加量较低时,产物中碳纳米管的直径减小,产量增多。当噻吩的添加量超过0.5%时,可以得到CNTs/FeNP杂化结构。使用X射线能谱仪、X射线衍射仪分析了杂化结构的成分及其相对含量,结果显示体系中的Fe主要以α-Fe、γ-Fe和Fe3C的形式存在,并且Fe的含量随噻吩含量的增加不断增加。通过研究纳米铁颗粒的形成及其在碳纳米管表面的沉积,揭示了CNTs/FeNP杂化结构的形成机理。     

载气种类对单壁碳纳米管管径的影响研究

单壁碳纳米管的管径对其性能、特别是储氢性能有极其重要的影响,但至今未见制备过程中系统控制单壁碳纳米管管径的报道.本文分别以氦气、氮气和氩气为载气,采用催化裂解法制备了不同直径范围的单壁碳纳米管.HRTEM和Raman光谱分析表明,以氦气、氩气为载气制得的碳管直径分布范围相对较窄,平均直径分别约为1.6和5.0nm.以氮气为载气时碳管直径分布相对较宽,约为2.0～4.5nm.氮气与碳反应生成氮化碳可能是导致单壁碳纳米管直径分布相对较宽的主要原因.分别以氦气、氮气和氩气为载气制得的单壁碳纳米管,在273K,15MPa时质量储氢分数依次为4.21%、6.30%和8.05%.     

氧化硅包覆单壁碳纳米管纳米电缆的制备(英文)

采用氢电弧放电法直接制备了无定形氧化硅包覆单壁碳纳米管同轴纳米电缆。纳米电缆的长度为几微米到数十微米,直径约为10～30 nm。纳米电缆的外包覆层为无定形氧化硅,每根电缆的芯部包含1根到几根单壁碳纳米管。单壁碳纳米管具有较高的结晶度,其直径主要集中在2.2 nm和1.8 nm。基于实验研究结果,提出了一种纳米电缆的生长机制。所制备的无定形氧化硅包覆单壁碳纳米管纳米电缆可望用于场效应晶体管等纳电子器件的构建。     

热膨胀石墨烯表面化学镀纳米镍

以热膨胀还原所制石墨烯为载体,采用超声辅助-化学镀法制得石墨烯担载Ni纳米复合材料。利用X射线衍射仪和透射电子显微镜和能谱仪分析其微观结构及元素组成,研究其化学镀镍的反应机理。结果表明,随施镀时间的延长,Ni纳米颗粒以Pd为自催化活性中心,逐步附着在石墨烯表面上,并随Pd纳米颗粒的分布情况而富集在石墨烯边缘及皱褶区域;Sn纳米颗粒对化学镀镍贡献较小,以致化学镀镍后仍有部分残留。可见,在石墨烯表面进行化学镀镍时,Pd对Ni纳米颗粒的生长成核起定位和催化作用。     

基于碳纳米管模板的氮化镓纳米线束合成

通过金属有机物化学气相沉积方法在碳纳米管模板上生长氮化镓纳米线束.对所生长的纳米结构进行了扫描电镜和X射线能谱分析,结果显示氮化镓纳米晶体可以与碳纳米管形成纳米线束状复合物.纳米线束状复合物直径为100～200 nm,长度为1.5～2.5μm,纳米线的两端呈现尖角状.由于氨气很容易吸附在碳纳米管表面,可知所获得的纳米结构的初始生长机制为碳纳米管的表面氮化.该研究也证明金属有机物化学气相沉积将是用于制造化合物纳米结构材料的一项有效的技术.     

新型一维材料--单壁碳纳米管的制备和应用研究

本文简要综述了单壁碳纳米管的最新进展.主要介绍了最近两年单壁碳纳米管的制备技术发展情况,包括电弧放电,化学气相沉淀,激光蒸发和太阳能方法.展望了其在储氢材料,纳米电子器件等领域的应用前景.讨论了影响单壁碳纳米管制备及实际应用的几个关键因素.提出了单壁碳纳米管的发展方向.     

石墨烯担载SnO2纳米复合材料的电化学性能研究

以热膨胀还原石墨烯为载体,采用超声辅助浸渍法制得一系列石墨烯担载SnO2纳米复合材料。利用X射线衍射(XRD)和透射电子显微镜(TEM)分析其微观结构,同时使用循环伏安法研究其相应电化学行为。结果表明:随浸渍时间延长,SnO2逐步占据石墨烯表面原有活性位(如含氧官能团和晶格缺陷),使其担载密度显著提高。但SnO2纳米颗粒对复合体系的赝电容贡献较小,同时其对石墨烯活性位具有掩蔽作用,反而导致石墨烯电容性能逐步下降。可见,石墨烯表面活性位对热膨胀石墨烯的电容性能起重要作用。     

Al-C-N非晶薄膜结构及导电性研究

为了揭示Al-C-N非晶薄膜的结构、导电性以及它们之间的关系,本文采用非平衡磁控溅射沉积技术在Si(100)基体上沉积得到了不同Al含量的Al-C-N薄膜。使用X射线光电子能谱仪、X射线衍射和高分辨透射电镜研究了所制备薄膜的相组成和微观结构。采用四引线法测定了薄膜电阻率-温度关系和霍尔电阻率-磁场关系。实验结果表明,所制备薄膜为非晶结构,结构致密,没有明显的缺陷,薄膜中主要的化学键为C-N,C-C和Al-N键。薄膜的成分对其导电性能有着明显的影响,当Al含量较低时,Al-C-N薄膜为p型半导体;当Al含量较高时薄膜转变为绝缘体。     

纳米Fe包覆Si3N4的制备及其高温烧结微观组织

采用非均相沉淀-热还原法制备了Fe/Si₃N₄颗粒复合粉末并在热处理温度1873K和0.1MPa氮气气氛下进行常压与热压烧结。通过扫描电镜(SEM)、透射电镜(TEM)、电子能谱(EDS)、X射线衍射(XRD)等方法观察Fe/Si₃N₄复合粉末的结构形貌及常压、热压烧结后的微观组织。结果表明：Fe/Si₃N₄复合粉末物相主要存在Fe相与Si₃N₄相,微观结构为纳米薄层 Fe均匀包覆Si₃N₄颗粒;高温烧结后的常压与热压样品的组织成分与微观结构有极大的不同,除了存在Si₃N₄相之外,常压样品金属Fe相衍射峰消失,并有晶粒粗大铁硅化合物生成,热压样品则保留有金属Fe相,并存在晶粒相对细小铁硅化合物及致密的玻璃态物质。     

Bimetallic iron and cobalt incorporated MFI/MCM-41 composite and its catalytic properties

The MFI/MCM-41 composite material with bimetallic Fe and Co incorporation was prepared using templating method via a two-step hydrothermal crystallization procedure. The obtained products were characterized by a series of techniques including powder X-ray diffraction, N₂ sorption, transmission electron microscopy, scanning electron microscope, H₂ temperature programmed reduction, thermal analyses, and X-ray absorption fine structure spectroscopy of the Fe and Co K-edge. The catalytic properties of the products were investigated by residual oil hydrocracking reactions. Characterization results showed that the FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of stable meso- and micro-porous structures. Iron and cobalt ions were incorporated into the silicon framework, which was confirmed by H₂ temperature programmed reduction and X-ray absorption fine structure spectroscopy. This composite presented excellent activities in hydrocracking of residual oil, which was superior to the pure materials of silicate-1/MCM-41.     

Fabrication of TiO<Subscript>2</Subscript>/ZnO composite nanofibers with enhanced photocatalytic activity

TiO₂/ZnO composite nanofibers have been successfully prepared by electrospinning technique. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Raman spectrum, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance spectroscopy, were used to characterize the as-synthesized nanofibers. The photocatalytic studies revealed that the TiO₂/ZnO nanofibers exhibited enhanced photocatalytic efficiency of photodegradation. Additionally, the recycling experiment of TiO₂/ZnO nanofibers had been done, demonstrating that TiO₂/ZnO nanofibers have high efficiency and stability.     

Preparation and electrochemical properties of carbon nanofiber composite dispersed with silver nanoparticles using polyacrylonitrile and beta-cyclodextrin

A simple one-step method was used for preparing the beta-cyclodextrin/polyacrylonitrile (PAN) nanofibers deposited with silver nanoparticles by electrospinning and followed by the reduction of the Ag+ ions. The nano-composite fibers were stabilized at 280 degrees C in air and activated at 800 degrees C for 1 h in steam/N2. The structures of nano-composite fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction analysis (XRD). The electrochemical behaviors of the composite of carbon nano-fibers were investigated by cyclic voltammetry and charge/discharge tests.     

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.     

Preparation and characterization of nanostructured MWCNT-TiO2 composite materials for photocatalytic water treatment applications

Nanoscale composite materials containing multi-walled carbon nanotubes (MWCNT) and titania were prepared by using a modified sol-gel method. The composites were comprehensively characterized by thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The analysis revealed the presence of titania crystallites of about 7.5 nm aggregated together with MWCNT in particles of 15-20 nm of diameter. The photoactivity of the prepared materials, under UV or visible irradiation, was tested using the conversion of phenol from model aqueous solutions as probe reaction. A synergy effect on the photocatalytic activities observed for the composite catalysts was discussed in terms of a strong interphase interaction between carbon and TiO₂ phases by comparing the different roles of MWCNT in the composite materials.     

A simple route to disperse silver nanoparticles on the surfaces of silica nanofibers with excellent photocatalytic properties

In this work, monodispersed silver nanoparticles decorated SiO₂ nanofibers were synthesized by electrospinning method, followed by thermal treatment at 600 °C. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) were used to characterize the composite nanofibers. Accordingly, the detailed formation mechanism of SiO₂/Ag composite nanofibers was discussed. Furthermore, an excellent catalytic activity of SiO₂/Ag composite fibers was observed by a degradation reaction of methyl orange (MO) dye.     

Photodegradation of organic dyes over nickel distributed CNT/TiO2 composite synthesized by a simple sol-gel method

In this study, the multi-walled carbon nanotubes were oxidized by m-chlorperbenzoic acid followed by the reaction with titanium n-butoxide and nickel nitrate to prepare Ni distributed CNT/TiO₂ composite by a simple sol-gel method. The functional groups formed on the surface of MWCNTs were analyzed by Fourier transform infrared spectroscopy. The prepared Ni distributed CNT/TiO₂ composite was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. The photodegradation of methylene blue, methylene orange and rhodamine B solution under UV irradiation was employed to test the photocatalytic activity of the Ni distributed CNT/TiO₂ composite. According to the results, Ni distributed CNT/TiO₂ composite showed very excellent photocatalytic activity to decompose MB, MO and Rh.B solutions, due to the electron absorption effect of MWCNTs and electron trapping effect of nickel.     

Cu/AAO复合材料的制备及表征

通过阶梯降压法,成功制备出带有铝基底的有序多孔阳极氧化铝,铝基底与有序多孔氧化铝之间的阻挡层极薄。以该模板为阴极,采用循环伏安法电化学沉积技术制备出Cu/AAO纳米复合材料。分别用场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线衍射(XRD)等测试方法对该纳米复合材料的形貌、组成和结构进行了表征和分析。结果表明,Cu纳米线在模板中填充率高,直径约为70nm,长度可达30μm,具有面心立方单晶结构。