压缩集结碳纳米管电极对活性艳红染料的电催化降解研究

采用浓硝酸回流、高温焙烧、高温焙烧结合高速球磨的方法对碳纳米管进行前处理. 通过低温氮吸附法测定碳纳米管的比表面积; 透射电子显微镜观察碳纳米管处理前后的形貌结构; 红外光谱分析碳纳米管处理前后的官能团变化; 拉曼光谱分析处理前后的碳纳米管中无定形碳和石墨碳含量的变化; 将处理前后的碳纳米管制成电极, 作为电催化阳极来处理模拟染料废水活性艳红X-3B溶液. 实验结果表明: 经处理后制成的碳纳米管电极, 其稳定性及对染料溶液的电催化降解效率都有显著提高, 高温焙烧结合高速球磨为最佳的前处理方法.     

真空加热活化法提高内嵌钴粒子的碳纳米管的水裂解产氢催化活性

采用真空加热活化法制备出高催化活性的内嵌金属钴纳米粒子的碳纳米管材料.通过增加碳纳米管材料的本征碳缺陷位点,显著提升了材料的催化活性(7倍).高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)和拉曼(Raman)光谱表征结果显示,真空加热活化增加了碳纳米管的本征碳缺陷,并减少了碳纳米管碳层的杂原子含量.电化学表征和电催化水裂解实验结果表明,增加碳纳米管的本征碳缺陷位既可以在碳纳米管上产生更多的催化位点,又可以提高碳纳米管界面的电荷迁移能力,进而提高对水裂解的催化性能.     

在不同激发波长下的单壁碳纳米管的拉曼光谱研究

采用直流电弧法制备单壁碳纳米管样品,用457.5和632.8nm两种不同的激发光分别测得单壁碳纳米管的正常拉曼光谱和共振拉曼光谱.通过理论分析得到了单壁碳纳米管的直径分布,进一步推测了其类型及结构参数;对单壁碳纳米管的正切拉伸模的成分进行了归属.在632.8nm激发波长下得到了IG/ID值随激光功率变化的曲线,认为在2.5mW时,单壁碳纳米管缺陷的结构可能发生了改变.在用457.5nm波长激发的单壁碳纳米管的拉曼光谱中,首次发现了1421cm-1的拉曼谱峰.     

纳米CaCO3负载过渡金属CVD法制备多壁碳纳米管的研究

以纳米碳酸钙粉体为载体,用浸渍法制备了可用于化学气相沉积(CVD)法制备碳纳米管的高产率催化剂.应用FESEM,HRTEM,TEM,XRD和激光拉曼谱对产物进行了表征.结果表明,由于纳米碳酸钙具有较大的比表面积,可高密度地承载催化剂活性组分.在碳纳米管生长初期,处于缓慢分解状态的纳米碳酸钙才能有效地起到载体作用,且反应温度为700～750℃时,碳纳米管的产率较高.Fe-Co双金属催化剂在700℃,催化生长60min后,可增重10倍,而且产物中无定形碳含量极少.纳米碳酸钙载体易于提纯,用质量分数为30%的硝酸超声提纯粗产品1h,可使纯度提高到97%,且不破坏碳纳米管结构.     

高温煅烧Mo改性的Fe／MgO催化剂用于制备管径分布均一的单壁碳纳米管

研究了在以甲烷化学气相沉积法制备单壁碳纳米管的过程中高温煅烧预处理(900℃煅烧10h)对Mo改性Fe/MgO催化剂的作用.发现这种预处理有利于Fe在催化剂中的稳定和分散,从而制备出管径均一的单壁碳纳米管.采用能谱元素分析、高分辨透射电镜、X射线衍射、比表面积测量、拉曼光谱和热重分析对样品进行了表征.结果表明,在碳纳米管生长的过程中,铁元素在催化剂表面富集,单壁碳纳米管生长于富集铁的纳米颗粒上,并存在碳管直径与铁颗粒尺寸的依赖关系.Mo存在时可煅烧形成FeMoO4复合氧化物,后者比MgFe2O4相更加稳定.Mo/Fe比例对提高单壁碳纳米管的生长密度、纯度与管径均一性等均有明显影响.上述研究对进一步精确控制制备单壁碳纳米管有重要意义.     

高温退火一步非破坏性纯化碳纳米管

针对催化化学气相法合成的碳纳米管含有金属、金属氧化物和碳杂质, 且缺陷较多进行了非破坏性纯化研究. 基于碳纳米管与碳杂质间结构、性质的微小差异, 1800 ℃使粗制的碳纳米管高温退火3 h, 为避免碳纳米管氧化, 高温退火过程在氩气气氛中完成. 运用扫描电镜、透射电镜观察碳纳米管的形貌和结构, 发现高温退火后, 碳纳米管的端帽大部分被打开. 能谱检测显示, 粗制的碳纳米管中的杂质(Al, Si, Ni, Cu 质量分数w分别为4.67%, 0.27%, 40.12%和1.34%)退火后被除去. 拉曼分析表明, 退火前后石墨D, G峰面积S_D, S_G分别从1314900降至474921, 767157降至566292, 退火不仅有效地去除了样品中的碳杂质, 而且使碳纳米管的缺陷得到一定程度的修复, 石墨化度随之大大提高. 研究提出了一种简单的、非破坏性的、便于规模化的纯化方法.     

新疆煤基碳纳米管的调控制备

以新疆产煤为碳源, 采用直流电弧放电法制备了不同管径的碳纳米管。利用场发射扫描电子显微镜、高倍透射电子显微镜、激光显微共聚焦拉曼光谱仪等对产物进行了表征。研究结果表明:在新疆大黄山、黑山和库车煤田的产煤中, 库车产煤是用直流电弧放电法制备碳纳米管的最优碳源。以此为原料, 镍粉和硫化亚铁混合物为催化剂, Ar气氛下可得到直径约为500 nm的竹节状碳纳米管, 其缺陷密度比相同条件下N₂和Ar气氛所得碳纳米管的缺陷密度小, 并探讨了Ar气氛下煤基竹节状碳纳米管的生长机理。     

新疆煤基碳纳米管的调控制备

以新疆产煤为碳源,采用直流电弧放电法制备了不同管径的碳纳米管。利用场发射扫描电子显微镜、高倍透射电子显微镜、激光显微共聚焦拉曼光谱仪等对产物进行了表征。研究结果表明:在新疆大黄山、黑山和库车煤田的产煤中,库车产煤是用直流电弧放电法制备碳纳米管的最优碳源。以此为原料,镍粉和硫化亚铁混合物为催化剂,Ar气氛下可得到直径约为500 nm的竹节状碳纳米管,其缺陷密度比相同条件下N2和He气氛所得碳纳米管的缺陷密度小,并探讨了Ar气氛下煤基竹节状碳纳米管的生长机理。     

碳纳米管在接枝二元胺过程中微结构的变化

通过对酸化的多壁碳纳米管(MWNTs)进行酰氯化, 在碳纳米管表面接枝己二胺. 用红外光谱、热重分析、拉曼光谱和场发射扫描电镜对处理前后的碳纳米管进行分析表征. 结果表明, 经过酰氯活化, 己二胺比较容易被接枝到碳纳米管上. 而且还发现碳纳米管在酸化后形成紧密块状结构, 在接枝胺后重新变得蓬松, 其表观比容甚至大于原始碳纳米管. 从理论上分析了碳纳米管的反应过程, 对碳纳米管在接枝胺过程中微结构的变化机理进行推测, 认为通过接枝, 己二胺插入碳纳米管之间, 改变了碳纳米管之间的相互作用, 使得酸化后因形成氢键而导致的紧密堆砌结构被破坏.     

MoS2/C复合纳米管的合成

在900℃氢气气氛下,通过热分解载有硫代钼酸铵的碳纳米管前驱物得到MoS₂/C复合纳米管.通过粉末X射线衍射(XRD)、拉曼光谱(Raman)、高分辨透射电镜(HRTEM)和X射线能量散射仪(EDS)等方法对其形貌、结构和成分进行了表征.结果表明,所合成物质是一种由两种材料组成管壁的新型纳米管.     

Purification of multiwalled carbon nanotubes by annealing and extraction based on the difference in van der Waals potential

The potential energies of van der Waals interactions between two multiwalled carbon nanotubes (MWNTs) as well as two carbon nanoparticles (CNPs) were calculated and compared on the basis of the continuum Lennard-Jones model. The well depth of the potential is 1 order of magnitude higher for MWNTs than for CNPs, indicating that MWNTs and CNPs can be separated from each other through polymer-induced steric stabilization. On the basis of this prediction, a novel method for the purification of MWNTs was proposed. The method involves a high-temperature annealing (2600 degrees C, 1 h) followed by an extraction treatment with a selected dispersing agent. While the annealing process evaporates the metal particles, the extraction treatment removes CNPs. The quality of the nanotubes obtained after purification was examined by laser Raman, thermogravimetric analysis, and electron microscopy observations.     

氨基化多壁碳纳米管的制备与表征

以多壁碳纳米管(MWNTs)为原料, 经自由基反应, 制备了氰基改性的多壁碳纳米管, 然后采用Al-NiCl₂·6H₂O-THF体系还原氰基得到了氨基化的碳纳米管。通过拉曼光谱仪、热重分析仪、X射线光电子能谱仪和透射电子显微镜对产物的结构与形貌进行了表征。结果表明:氨基通过共价键枝接在MWNTs的表面, 氨基化多壁碳纳米管每1000个表面碳原子中有17.1个转化为氨基;该反应条件温和, 反应时间短, 且不破坏MWNTs的结构。     

原位缩聚法制备碳纳米管/尼龙11复合材料

用原位缩聚法制备了碳纳米管增强的尼龙11复合材料,用X射线衍射仪、红外(FTIR)、扫描电镜(SEM)、热重(TGA)、机械拉伸测试仪等对其结构、形貌、热性能及机械性能进行了表征测试.扫描电镜结果显示碳纳米管均一地分散在尼龙11/碳纳米管复合材料中.复合材料的拉伸模量比纯尼龙11有较大的提高.当复合材料中碳纳米管含量分别为1%,5%,10%时,材料的拉伸模量分别提高了34.5%,92.9%和113,7%.同时,复合材料的储能模量也有提高.热分析结果显示当复合材料中碳纳米管含量为1%时,其失重5%和10%的温度分别由纯尼龙11的404℃、424℃提高到414℃和437℃.示差扫描量热分析(DSC)显示复合材料的结晶温度随碳纳米管的加入而升高,而结晶度则降低.     

氨基化多壁碳纳米管的制备与表征

以多壁碳纳米管(MWNTs)为原料,经自由基反应,制备了氰基改性的多壁碳纳米管,然后采用Al-NiCl2.6H2O-THF体系还原氰基得到了氨基化的碳纳米管。通过拉曼光谱仪、热重分析仪、X射线光电子能谱仪和透射电子显微镜对产物的结构与形貌进行了表征。结果表明:氨基通过共价键枝接在MWNTs的表面,氨基化多壁碳纳米管每1000个表面碳原子中有17.1个转化为氨基;该反应条件温和,反应时间短,且不破坏MWNTs的结构。     

Formation of carbon nanotubes in water by the electric-arc technique

A simplified arc discharge apparatus was used for growing carbon nanotubes, required only water (solution) in a glass container with no need for vacuum, water-cooled chamber. Carbon nanotubes with highest purity (20%) and highest yield (7 mg/min) were obtained when using salt solution as the medium. Resonance Raman spectrum of multi-walled carbon nanotubes (MWNTs) presented in as-grown materials was measured and RBM peaks originating from very thin core nanotubes were observed. The results show that high-quality MWNTs can be effectively prepared in water-arcing process.     

Polyurea-functionalized multiwalled carbon nanotubes: synthesis, morphology, and Raman spectroscopy

An in situ polycondensation approach was applied to functionalize multiwalled carbon nanotubes (MWNTs), resulting in various linear or hyperbranched polycondensed polymers [e.g., polyureas, polyurethanes, and poly(urea-urethane)-bonded carbon nanotubes]. The quantity of the grafted polymer can be easily controlled by the feed ratio of monomers. As a typical example, the polyurea-functionalized MWNTs were measured and characterized in detail. The oxidized MWNTs (MWNT-COOH) were converted into acyl chloride-functionalized MWNTs (MWNT-COCl) by reaction with neat thionyl chloride (SOCl2). MWNT-COCl was reacted with excess 1,6-diaminohexane, affording amino-functionalized MWNTs (MWNT-NH2). In the presence of MWNT-NH2, the polyurea was covalently coated onto the surfaces of the nanotube by in situ polycondensation of diisocyanate [e.g., 4,4'-methylenebis(phenylisocyanate)] and 1,6-diaminohexane, followed by the removal of free polymer via repeated filtering and solvent washing. The coated polyurea content can be controlled to some extent by adjusting the feed ratio of the isocyanato and amino groups. The structure and morphology of the resulting nanocomposites were characterized by FTIR, NMR, Raman, confocal Raman, TEM, EDS, and SEM measurements. The polyurea-coated MWNTs showed interesting self-assembled flat- or flowerlike morphologies in the solid state. The signals corresponding to that of the D and G bands of the carbon nanotubes were strongly attenuated after polyurea was chemically tethered to the MWNT surfaces. Comparative experiments showed that the grafted polymer species and structures have a strong effect on the Raman signals of polymer-functionalized MWNTs.     

Renewable nanocomposite layer-by-layer assembled catalytic interfaces for biosensing applications

A novel, easily renewable nanocomposite interface based on layer-by-layer (LbL) assembled cationic/anionic layers of carbon nanotubes customized with biopolymers is reported. A simple approach is proposed to fabricate a nanoscale structure composed of alternating layers of oxidized multiwalled carbon nanotubes upon which is immobilized either the cationic enzyme organophosphorus hydrolase (OPH; MWNT-OPH) or the anionic DNA (MWNT-DNA). The presence of carbon nanotubes with large surface area, high aspect ratio and excellent conductivity provides reliable immobilization of enzyme at the interface and promotes better electron transfer rates. The oxidized MWNTs were characterized by thermogravimetric analysis and Raman spectroscopy. Fourier transform infrared spectroscopy showed the surface functionalization of the MWNTs and successful immobilization of OPH on the MWNTs. Scanning electron microscopy images revealed that MWNTs were shortened during sonication and that LbL of the MWNT/biopolymer conjugates resulted in a continuous surface with a layered structure. The catalytic activity of the biopolymer layers was characterized using absorption spectroscopy and electrochemical analysis. Experimental results show that this approach yields an easily fabricated catalytic multilayer with well-defined structures and properties for biosensing applications whose interface can be reactivated via a simple procedure. In addition, this approach results in a biosensor with excellent sensitivity, a reliable calibration profile, and stable electrochemical response.     

聚噻吩/多壁碳纳米管复合材料的导电性能

通过共混多壁碳纳米管(MWNTs)和聚噻吩(PTh), 制备了PTh/MWNTs复合材料, 复合材料表现出良好的导电性能(电导率达16.1 S/m). 通过Raman, TG, XPS, UV-Vis等对复合材料进行了分析, 结果表明, MWNTs和 PTh之间存在强的相互作用, MWNTs上的离域电子与噻吩共轭主链上的π电子之间形成π-π共轭, 电子从MWNTs转移到聚噻吩, 增加了噻吩主链的有效共轭长度, 提高了复合材料的导电性能. FESEM分析表明, MWNTs和它周围被掺杂的聚噻吩通过π-π共轭作用结合在一起, 形成相对独立的导电单元, 在复合材料的导电体系中起到主要作用.