调变Ni／Mo／MgO催化剂中Ni／Mo比例可控合成薄壁碳纳米管

采用摩尔分数1%Ni及负载少量Mo的Ni/MO/MgO催化剂裂解甲烷合成薄壁碳纳米管.通过SEM、TEM、XRD和Raman光谱表征方法研究了碳纳米管直径和催化剂中Ni/Mo比例关系.实验发现:通过控制Ni/Mo比例可以调变催化剂颗粒大小以及活性相.TEM及XRD表征发现,随着Ni/Mo比例的降低,金属Mo相逐渐从NiMo合金相中析出.NiMo合金相对应的活性组分颗粒很小,容易催化裂解甲烷形成薄壁碳纳米管;而后析出的Mo相则主要形成了大管径厚壁的碳纳米管.当Ni/Mo比例为6时可以高选择性地获得窄分布,内径为1.3nm,外径为3.0nm的溥壁碳纳米管.Raman光谱进一步验证了碳纳米管含有较少的缺陷.薄壁碳纳米管形成的关键因素主要体现为碳在其表而的快速扩散以及小颗粒的碳纳米管催化剂活性相控制.     

流动催化热解法制备高质量多壁碳纳米管的研究

以甲烷为碳源,N2和H2作载气,二茂铁作催化剂前驱体,采用流动催化热解法制备出大量高质量取向性好的多壁碳纳米管(MWCNTs)。利用扫描电子显微镜(SEM),透射电子显微镜(TEM)和Raman光谱对碳纳米管的形貌和结构进行了表征。该制备过程工艺简单并且成本低廉,对实现碳纳米管的规模生产具有重要意义。     

单壁碳纳米管的制备及生长特性研究

采用Fe/MgO作为催化剂 ,催化裂解CH4制备了较纯的单壁碳纳米管 ,用TEM和Raman对碳纳米管进行了表征 ,对不同生长温度下制备的碳纳米管Raman径向呼吸振动峰 (RBM)进行了分析 ,研究了生长温度对单壁碳纳米管生长特性和结构特性的影响     

一种适于碳纳米管制备的绿色前驱体

根据绿色化学原理尝试探索一种合成多壁碳纳米管的天然可再生前驱体.应用化学气相沉积(CVD)法,采用一种天然可再生前躯体(椰仁油),通过系列步骤合成了MWCNTs.氮气既作为气化前驱体载气(气体流速:100mL/min)又维持合成在惰性氛围中进行.合成的MWCNTs使用SEM、EDX、TEM和Raman表征,最佳条件下得到的碳纳米管直径为80nm～90nm.     

用二胺在碳纳米管上引入胺基团的研究

为了在碳纳米管上引入胺基团，先对CVD法制备的多壁碳纳米管进行了有效的纯化和功能化，用TEM观察了纯化过程中的杂质变化和碳纳米管的形态结构，然后用二环己基碳二亚胺(DEC)缩合剂使功能化了的多壁碳管和乙二胺反应，并采用FF-IR红外光谱和Raman光谱对反应前后的碳管进行了表征。红外光谱测试结果表明：反应前红外光谱中在1709cm^-1处有羧基的吸收峰，说明碳纳米管的端口及侧壁已被有效功能化；反应后在1581cm^-1出现吸收峰表明二者通过酰胺键连接起来，增强了碳纳米管在有机溶剂中的溶解性；Raman光谱中反应前后D峰和G峰无明显区别，表明反应前后碳纳米管结构未发生变化。     

铁催化分解二甲硫醚制备碳纳米管的研究

以二甲硫醚为碳源,Fe/MgO为催化剂,采用化学气相沉积法制备了碳纳米管。通过SEM、Raman、XRD、TEM表征方法研究了实验合成条件对碳纳米管产物的形貌和微结构的影响。结果表明,二甲硫醚的蒸汽浓度对碳纳米管的形貌和产量有重要影响。较高的二甲硫醚浓度会使催化剂的活性降低,制备出的碳纳米管较短且石墨化程度也较差。生长碳纳米管的最佳二甲硫醚浓度范围为2.69%～3.86%,且碳纳米管产物中有Y型碳纳米管的生成,并对其生长机理进行了初步讨论。     

化学气相沉积法制备定向碳纳米管及其生长机理的研究

以环己烷为碳源,二茂铁作催化剂,采用浮动催化化学气相沉积法制备了定向碳纳米管,并用SEM、TEM及Raman光谱对样品进行了鉴定和表征.并从不同的角度,提出了定向碳纳米管遵循底部生长的机理.     

大面积取向生长碳纳米管的ECR-CVD方法制备与表征

本文采用电子回旋共振微波等离子体化学气相沉积方法(ECR-CVD),以CH4和H2为气源、Fe3O4 纳米粒子为催化剂,未加电场,在多孔硅基底上制备出大面积取向生长碳纳米管.使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线能量色散分析(EDX)对样品形貌和结构进行表征.结果显示:合成的碳纳米管为多壁碳管;碳纳米管直径60 nm～90 nm,长度约8 μm;碳纳米管展现出中空管状和链状两种结构;碳纳米管的生长采取催化剂底端生长模式.     

多壁碳纳米管在硫酸溶液中的γ辐射剪切

在硫酸溶液中系统地研究了γ辐射法剪切多壁碳纳米管,以及影响碳管长度的反应条件,详细讨论了多壁碳纳米管的剪切机理.采用透射电子显微镜(TEM)、傅立叶变换红外光谱(FT-IR)、紫外可见分光光度计(UV-Vis)和Raman光谱对短多壁碳纳米管进行了分析与表征,分析了多壁碳纳米管浓度与其对UV270nm吸光度的关系,得出了多壁碳纳米管质量浓度与其对UV270nm吸光度的线性回归方程.结果表明,γ辐射和硫酸氧化作用在剪切多壁碳纳米管的过程中存在协同效应.随着辐射剂量和酸浓度的增加,剪切后的碳管长度不断缩短.当辐射剂量增加到200kGy、酸浓度为5mol/L时,短多壁碳纳米管长度为200～300nm.辐射剪切的方法在碳纳米管外侧及末端引进C-OH、-COOH等官能团,从而对MWNTs的石墨型结构造成微弱损伤.另外,制备的短多壁碳管在水中可以均匀分散2周而不出现沉淀.     

洁净单壁碳纳米管在Fe2O3／Al2O3二元气凝胶催化剂上的水辅助合成

分别以甲烷-氧气和甲烷-氢气-水的混合气作为反应气源,利用Fe2O3/Al2O3二元气凝胶作为催化剂于900℃反应30min合成了单壁碳纳米管.并采用SEM、XRD、TEM,高分辨透射电子显微镜(HRTEM)以及Raman光谱等分析技术对所制得的碳产物的结构和形貌进行了表征,以研究反应气氛中水蒸气的引入对单壁碳纳米管生长的影响.结果表明:反应气氛的组成对最终所形成的碳产物的产率和结构有着密切的关联.通过控制氢气载入甲烷-氢气-水的混合气氛中水蒸气的量可以合成低无定形碳的沽净单壁碳纳米管.     

多孔纳米碳纤维的制备及其在超级电容器中的应用研究

利用溶胶凝胶燃烧法制备了碱金属氧化物掺杂的铜催化剂,并使用这种催化剂在不同的温度、掺杂比例下通过热CVD法合成出了具有多孔分叉结构的纳米碳纤维.通过TEM、HRTEM、BET和激光拉曼光谱等手段对产物进行表征,显示这种纳米碳纤维的比表面积可高达1162m2/g,远高于普通的碳电极材料,并且具有非常丰富的中孔结构,克服了常规碳纳米纤维在应用中表现出的相对有效利用面积不大,比电容不高等缺陷,具备做电极材料的潜力.在将其应用于超级电容器电极材料后,利用二次电池测试仪及电化学工作站对其进行了循环伏安曲线及恒流充放电曲线的测试,结果显示这种纳米碳纤维具有良好的电化学电容行为,电极的可逆性良好,并且比电容值高达203F/g.这些发现将有助于碳纳米材料可控制备的研究,并且提供了一种有一定应用潜力的超级电容器电极材料.     

Facile synthesis route of graphene-like structures from multiwall carbon nanotubes

Graphene-like nanostructures were synthesized from multiwall carbon nanotubes through chemical exfoliation route in mild conditions. For this purpose multiwall carbon nanotubes were synthesized by Chemical Vapor Deposition method using Al-Fe-Co catalyst and treated with KMnO₄. The obtained nanostructures were characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM and TEM methods. FTIR results show that, treating the carbon nanotubes with KMnO₄ decorates their surface with oxygen containing functional groups. XRD and Raman spectroscopy results reveal that the outermost layers of the nanotubes were exfoliated during the treatment. The formation of graphene-like nanostructures was confirmed by SEM and TEM methods. The novelty of this work is the first time use of this type of mild and cheap condition for obtaining graphene-like nanostructures from MWCNTs without any other intermediate treatment.     

化学气相沉积法合成碳纳米管及其导电性能研究

以二甲硫醚为碳源前驱体,Co/MgO为催化剂,采用化学气相沉积法生长出碳纳米管及Y形碳纳米管,此法稳定性及重现性较好.通过扫描电子显微镜、透射电子显微镜、拉曼光谱及X射线衍射对产品形态和结构进行了分析和表征,结果表明,所制备的碳纳米管形态较规整、纯度较高,具有较好的石墨微晶结构;导电性能测试结果显示,Y形碳纳米管各分支均呈现出典型的金属性导电性能.     

Bulk scale production of carbon nanofibers in an economical way

An economical route for the scalable production of carbon nanofibers (CNFs) on a sodium chloride support has been developed. CNFs have been synthesized by chemical vapor deposition (CVD) method by using metal formate as catalyst precursors at 680°C. Products were characterized by SEM, TEM, Raman spectroscopy and XRD method. By thermal analysis, the purity of the as grown products and purified products were determined. This method avoids calcination and reduction process which was employed in commercial catalysts such as metal oxide or nitrate. The problems such as detrimental effect, environmental and even cost have been overcome by using sodium chloride as support. The yield of CNFs up to 7800 wt.% relative to the nickel catalyst has been achieved in the growth time of 15 min. The advantage of this synthesis technique is the simplicity and use of easily available low cost precursors.     

超临界干燥法制备催化剂合成单壁纳米碳管及表征

采用超临界干燥法制备了活性高、比表面大的Fe/Mo/Al₂O₃催化剂.通过超临界干燥,催化剂的比表面由294m²/g提高到401m²/g.在1000℃下用该催化剂催化裂解甲烷, 合成了大产量、高质量的单壁纳米碳管(SWNTs).利用SEM、TEM、HRTEM、TGA 和Raman等手段对所制备的SWNTs进行了表征.结果表明:超临界法制备催化剂合成的粗产品中SWNTs含量在30%以上,大大高于同一配方催化剂采用常规干燥法的产率(约2%); SWNTs的管径分布在0.8-1.0nm之间,其形态以束状为主.     

A simple method of producing single-walled carbon nanotubes from a natural precursor: Eucalyptus oil

Single-walled carbon nanotubes (SWNTs) have been synthesized by catalytic decomposition of eucalyptus oil, on a high silica-zeolite support impregnated with Fe/Co catalyst at 850 °C by the spray pyrolysis method. Catalyst with 5 wt.% (molar ratio of Co:Fe = 1:1), impregnated in zeolite was suitable for effective formation of carbon nanotubes (CNTs). As-grown CNTs were characterized by SEM, TEM and Raman spectroscopy. Raman spectroscopy reveals that as-grown CNTs are well graphitized. Raman spectroscopy also reveals that the as-prepared SWNTs have a diameter of about 0.79-1.71 nm.     

Fabrication of flat capped carbon nanotubes using an arc-discharge method assisted with a Sm-Co catalyst

In this study, carbon nanotubes (CNTs) were fabricated using an arc-discharge method assisted with samarium-cobalt (Sm-Co) chloride as a catalyst. The optimal fabrication condition was determined through a series of experiments on various ambient conditions. Observations were completed using scanning electron microscopy (SEM), Raman spectroscopy, and tunneling electron microscopy (TEM); the main products we observed are well-structured multi-walled carbon nanotubes. By identifying the radial breathing modes (RBMs) of the Raman spectra with a TEM micrograph, we also observed a small number of single-walled carbon nanotubes. With the assistance of the Sm-Co chloride catalyst, the RBMs of the Raman spectra were measured in the ambient pressure of 760 torr. The TEM observations revealed that our nanotubes have good graphitic structures and almost no bamboo defects, which agrees with their Raman measurements with a high I_G/I_D ratio (~88). A perfect graphitic flat cap was found to be attached at the end of the nanotube. Simulation shows that by incorporating 5 carbon pentagons, it is possible to construct a flat capped carbon nanotube. The results of our experiment offer a unique approach to growing high quality CNTs. Such a flat capped structure may useful for further advanced application in nano-electronics and nano-optics.     

微波辐照液相法合成石墨烯

以天然鳞片石墨为原料, 采用Hummers法先制备出石墨氧化物, 再采用微波辐照法在N-甲基吡咯烷酮(NMP)溶剂中合成出石墨烯. 微波辐照选择性地加热NMP溶剂, 同时石墨氧化物因其含氧官能团分解成CO、CO₂、H₂O气体而得以剥离和还原. 通过XRD、SEM、EDS、TEM、HRTEM、SAED、XPS和Raman测试手段对所合成的石墨烯进行了表征. 结果表明, 所合成的石墨烯尺寸为几微米, 呈透明绢丝状结构, 每个石墨烯片含有2~5层石墨层; 所合成的石墨烯可以均匀地分散在NMP溶剂中.     

椰子油制炭微管(英文)

报道了采用可再生的天然前驱体(椰子油),通过化学气相沉积制备一种"高长径比"的新型碳管结构,炭微管(CMTs)的方法。CMTs合成工艺:N2气氛,合成温度1175℃,流速100mL/min,二茂铁为催化剂。合成的CMTs利用SEM,EDX,TEM,和Raman光谱表征。结果表明:合成的CMTs的直径为1.7μm～2.1μm,并具有高的长径比。     

Effect of sonication time on the synthesis of the CdS nanoparticle based multiwall carbon nanotube – maleic anhydride – 1-octene nanocomposites

Effect of sonication time on the synthesis of the CdS nanoparticles within the matrix obtained through the covalent functionalization of multiwall carbon nanotube (MWCNT) with maleic anhydride (MA) – 1-octene copolymer was investigated. Cadmium chloride and thiourea were used as the raw materials. MWCNTs used for the matrix were synthesized by Catalytic Chemical Vapor Deposition using Fe-Co/Al₂O₃ as the catalyst. The obtained nanostructures were characterized by FTIR, XRD, Raman spectroscopy, TEM, SEM, TG and UV-Vis spectroscopy. Electrophysical properties of the polymer nanocomposites obtained using different periods of time for sonication were comparably investigated. The average CdS particle diameter was between 3.9–7.9 nm as confirmed independently by TEM and XRD. UV-Vis spectroscopy revealed that the obtained nanostructures are appropriate base materials for making optical devices.