碳纳米管表面修饰铜纳米粒子的制备及表征

以糠醇为碳源,模板(AAO)碳化法制备了高纯度的碳纳米管,硝酸铜作为金属源,以溶液浸渍法合成了碳纳米管表面修饰的铜纳米粒子。利用XRD、TEM、SEM、能谱仪和拉曼分析等手段对样品进行了结构和形貌的表征。结果表明:粒径为10~20nm的铜纳米颗粒均匀负载到孔径在90~100nm的碳纳米管表面。电子衍射证明,这些颗粒为单质铜和Cu2O的纳米单晶,且铜纳米粒子具有很好的结晶度。     

NiO包覆Ni纳米颗粒的制备及其氧化特性研究

通过对直流电弧等离子体制备的Ni纳米颗粒钝化处理得到NiO包覆Ni纳米颗粒。并对试样的组成成分、形貌、晶体结构、粒度和氧化特性采用高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)、透射电子显微镜(TEM)和选区电子衍射(SAED)、热重和差示扫描量热分析仪(TGA/DSC)等手段进行分析。结果表明:经过表面钝化处理的NiO包覆Ni纳米颗粒具有明显的核-壳结构,内核为纳米Ni,外壳为NiO氧化物。颗粒呈球形,粒度均匀,分散性良好,粒径分布在20~70nm范围内,平均粒径为44nm,壳层氧化膜的厚度为5~8nm。壳核结构防止了纳米Ni颗粒的进一步氧化和团聚。     

碳纳米管承载纳米Fe_3O_4颗粒的制备(英文)

采用一种简单又经济的方法将Fe3O4纳米颗粒填充到碳纳米管中。透射电镜(TEM)、扫描电镜(SEM)及其能谱附件(EDX)和X射线多晶衍射(XRD)测试结果表明:Fe3O4纳米颗粒成功地填充到碳纳米管中。材料的磁性能测试结果表明:碳纳米管中填充Fe3O4纳米颗粒后,在常温下具有超顺磁性,其饱和磁化强度由0.35emu/g增大到了13.15emu/g。Fe3O4纳米颗粒填充的碳纳米管可望应用于工程和医学领域。     

直流碳弧法制备碳包覆铁纳米颗粒机理研究

采用直流碳弧等离子体法成功制备了碳包覆铁纳米颗粒,利用透射电子显微镜和高分辨透射电子显微镜、X射线衍射、X射线能谱仪对样品的形貌、物相结构、化学成分和粒度进行表征分析,并对碳包覆纳米金属颗粒的形成机理进行初步探讨。结果表明:直流碳弧等离子体技术制备的碳包覆纳米金属颗粒具有明显的铁核(bcc-Fe)/碳壳(石墨层片)包覆结构,颗粒大多呈球形和椭球形,粒径分布在20~60nm范围,平均粒径为44nm,铁粒子外碳层的厚度为5~8nm。碳包覆铁纳米铁颗粒是通过颗粒内部固态形式的碳自行扩散至颗粒表面和颗粒外部气态形式的碳沉积到颗粒表面形成的。     

基于开尔文探针力显微镜的纳米复合材料次表面成像分析

针对聚合物纳米复合材料次表面结构高分辨无损检测的需求,应用开尔文探针力显微镜(KPFM)对聚合物中导电填充物进行次表面纳米成像.首先,建立探针-纳米颗粒-基质体系的静电相互作用理论模型,分析聚合物中金属颗粒检测的成像机理;其次,通过有限元软件模拟并结合理论模型,系统研究针尖与样品间距、针尖半径等因素的影响;最后,制作聚合物和碳纳米管复合材料样品并进行基于KPFM的内部碳纳米管成像实验验证.结果表明:当针尖半径大约为1.5倍颗粒直径、间距较小时,成像效果较好;相较而言,探针锥角对成像结果影响不显著;KPFM对相对介电常数在3~10之间、颗粒直径越大、掩埋深度越小的内部纳米颗粒成像效果越好.     

离子液体辅助水热合成CeO_2纳米棒（英文）

以CeCl6·6H2O和NH3·6H2O为原料,使用离子液体1-丁基-3甲基咪唑氯盐([Bmim]Cl)辅助水热法在160℃下合成了Ce O2纳米棒。采用X射线衍射(XRD)和高分辨透射电子显微镜(HRTEM)对样品的结构和形貌进行了表征。实验结果表明:使用离子液体辅助水热法制备的产物为Ce O2纳米棒,而没有离子液体时产物则为外形无规则的纳米颗粒。所制备的纳米棒直径为13~25 nm,长度为200~500 nm。增大离子液体的用量将得到纳米颗粒。此外,升高水热温度至180℃所得样品为直径19~24 nm的纳米球,该纳米球由2 nm的纳米晶团聚而成。     

微波多元醇法制备单分散Ni1-xZnxFe2O4/MWCNTs与磁性能

以多壁碳纳米管(MWCNTs)为模板,三乙二醇(TREG)为溶剂,采用微波多元醇法制备MWC-NTs负载组成可控的Ni1-xZnxFe2O4(x=0.4、0.5、0.6)纳米复合材料Ni1-xZnxFe2O4/MWCNTs。其结构和形貌通过XRD、SEM、TEM和EDX进行表征,用VSM测试样品的磁性,并探讨了微波功率、微波时间对镍锌铁氧体负载的影响。结果表明立方系尖晶石结构的单分散Ni1-xZnxFe2O4磁性纳米粒子均匀负载在碳纳米管表面,平均粒径约为6nm;其磁性能与镍锌铁氧体的组成有关,随着Zn含量的增加,饱和磁化强度(Ms)先增大后减小,当x=0.5时Ms达到最大值。矫顽力(Hc)都比较小,在室温下表现为超顺磁性。     

阴离子对掺杂Co2+纳米Ni（OH）2性能的影响

为了考察阴离子种类对掺杂Co2+纳米Ni(OH)2性能的影响,采用不同镍盐制备出掺杂Co2+纳米Ni(OH)2,并采用X射线衍射(XRD)、透射电子显微镜(TEM)、循环伏安技术(CV)和恒流充放电方法对材料物化性能和电化学性能进行了研究.研究结果表明,掺杂Co2+的纳米Ni(OH)2为β-Ni(OH)2,衍射峰发生明显宽化.样品颗粒的尺寸为60~100 nm,阴离子的变化对制得的Ni(OH)2的表观形貌有影响.恒流充放电实验表明,阴离子为NO3-时,样品的质量比容量较高,0.2 C放电达到了234.6 mAh.g-1.循环伏安测试表明,阴离子为SO42-时,样品有较好的可逆性,阴离子为NO3-或SO42-时有较高的质子扩散系数.     

金属钴填充碳纳米管的微结构研究

以Co/硅胶为催化剂,采用化学催化法制备了金属Co填充的碳纳米管,并用高分辨透射电镜(HRTEM),微区电子衍射(SAED)及纳米束能谱分析(EDS)等现代手段对碳纳米管和填充物的形态和微结构进行了深入研究.结果表明,本实验采用的方法能获得大量的被金属Co填充的碳纳米管,填充物为具有面心立方结构的α-Co,填充的α-Co经常出现孪晶.本文还阐明了整个填充的微观过程并对生长机理进行了初步探讨.     

碳包覆NiO纳米颗粒的制备与性能

采用直流电弧放电等离子体技术成功制备了碳包覆NiO(NiO@C)纳米颗粒,并对样品的形貌、晶体结构、粒度、比表面积和孔结构采用高分辨透射电子显微镜、X射线衍射、X射线能量色散分析谱仪、拉曼散射光谱和N_2吸-脱附等测试手段进行了分析。实验结果表明:直流电弧等离子体技术制备的NiO@C纳米颗粒具有典型的核壳结构,内核为面心立方结构的NiO纳米颗粒,外壳为碳层。颗粒形貌主要为立方体结构,粒度均匀,分散性良好,粒径分布在30~70nm范围,平均粒径为50nm,外壳碳层的厚度为5nm。NiO@C纳米颗粒BET比表面积为28m~2/g,等效直径为46nm,与TEM和XRD测得的结果基本一致。Raman光谱说明样品中碳包覆层的石墨化程度较低,发生了红移现象。     

预置镍化学气相沉积法制备定向碳纳米管(英文)

采用化学气相沉积法(CVD),在溅射了镍薄膜的硅基底上制备了定向碳纳米管薄膜。对镍薄膜的氨气预处理过程及其机理进行了研究。结果发现预处理后的岛状区域随着薄膜厚度的增加而增加,纳米粒子区域的变化则与之相反。对5nm的镍薄膜进行预处理能获得细化和均匀分布的纳米粒子,有利于定向碳纳米管的生长。碳纳米管的生长过程及其细微结构与温度有很大关系。碳源的分解、碳原子在催化剂内部的扩散以及催化剂粒子的团聚三者之间的竞争决定了碳纳米管的生长情况。本文分析了碳纳米管的顶部生长模式及该模式下催化剂粒子的形态变化。     

等离子体射流辅助双催化剂原位催化法合成碳纳米管

以甲烷为碳源，Fe2O3／Ni为固定相催化剂，在常压条件下利用等离子体射流的高温将甲烷裂解生成碳自由基和氢气。同时联合原位催化法将碳自由基在Fe2O3／Ni双催化剂的共同作用下生长出碳纳米管。运用TEM和元素分析等测试手段对所得碳纳米管进行形貌、含量、结构的表征分析。结果表明，在一定反应条件下，可获得外径为10nm-30nm，管长约数百纳米、产率为75％左右的碳纳米管。与单催化剂相比，双催化剂的联合催化作用更有利于碳管的生长。     

乙酰丙酮铁为催化剂源在碳纤维表面生长碳纳米管的工艺研究

以乙酰丙酮铁为催化剂源,三甘醇为溶剂,通过溶剂热法在碳纤维表面负载催化剂前驱体,在H2与N2中一定温度下进行还原,采用化学气相沉积法在碳纤维表面生长碳纳米管。研究了催化剂的负载条件和碳纳米管的生长条件,采用XRD、FTIR、RAMAN对乙酰丙酮铁在三甘醇中反应在碳纤维表面负载催化剂前驱体产物进行分析,用SEM、TEM对催化剂前驱体粒子及碳纳米管的形貌进行表征。结果表明:催化剂前驱体为粒径30nm左右的Fe3O4颗粒,当催化剂的还原温度为415℃、还原时间为60min时,Fe3O4颗粒还原成纳米Fe颗粒;当碳纳米管的生长温度为750℃、生长时间为30min、气流体积比为V(N2)∶V(H2)∶V(C2H2)=50∶10∶10时能在碳纤维表面生长出形貌均一、管径为30~60nm的碳纳米管。     

Magnetic properties and transmission electron microscopy studies of Ni nanoparticles encapsulated in carbon nanocages and carbon nanotubes

Three types of carbon nanomaterials, including bamboo-shaped carbon nanotubes with Ni encapsulated and hollow and Ni catalytic particles filled carbon nanocages, have been prepared by methane catalytic decomposition at a relatively low temperature. Transmission electron microscopy observations showed that fascinating fullerene-like Ni–C (graphitic) core–shell nanostructures predominated. Detailed examination of high-resolution transmission electron microscopy showed that the walls of bamboo-shaped carbon nanotubes with quasi-cone catalytic particles encapsulated consisted of oblique graphene planes with respect to the tube axis. The Ni particles encapsulated in the carbon nanocages were larger than that encapsulated in carbon nanotubes, but the diameters of the cores of hollow carbon nanocages were less than that of Ni particles encapsulated in carbon nanotubes, suggesting that the sizes of catalyst particles played an important role during carbon nanomaterial growth. The magnetic properties of the carbon nanomaterials were measured, which showed relatively large coercive force (H_c = 138.4 O_e) and good ferromagnetism (M_r/M_s = 0.325).     

Template directed formation of nanoparticle decorated multi-walled carbon nanotube bundles with uniform diameter

Bundles of multi-walled carbon nanotubes of uniform diameter decorated with Ni nanoparticles were synthesized using mesoporous silicates as templates. The ordered morphology and the narrow pore size distribution of mesoporous silicates provide an ideal platform to synthesize uniformly sized carbon nanotubes. In addition, homogeneous sub-10?nm pore sizes of the templates allow in?situ formation of catalytic nanoparticles with uniform diameters which end up decorating the carbon nanotubes. The resulting carbon nanotubes are multi-walled with a uniform diameter corresponding to the pore diameter of the template used during the synthesis that are decorated with the catalysts used to synthesize them. They have a narrow size distribution which can be used in many energy related fields of research.     

Filling carbon nanotubes with particles

The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.     

Preparation of Cu nanoparticles on carbon nanotubes by solution infusion method and calcining in ambient atmosphere

Copper nanoparticles were synthesized using carbon nanotubes as a template. The process involved neither pre-purification nor an additional reducing agent. This method was simple and the Cu nanoparticles were uniformly loaded on the carbon nanotubes. TEM, SEM, XRD and EDX were used to examine the morphology of the Cu particles. The diameter of the carbon nanotubes is about 70-90 nm and the size of the nanoparticles is about 50-70 nm.     

In situ synthesis of ceria decorated carbon nanotubes by chemical vapor deposition

Ceria decorated carbon nanotubes (CNTs) were in-situ synthesized by chemical vapor deposition using a Ni/Ce/Cu catalyst. Ceria nanoparticles, with a diameter of about 3-8 nm, were highly dispersed on the CNTs, and it is believed that they are formed at the same time as the CNTs.     

碳负载尺寸可控的铂纳米粒子微波合成和表征

分别以XC-72碳和碳纳米管为载体,H₂PtCl₆为前驱体,用微波辐射加热的方法合成了碳负载的铂纳米粒子,并对其进行了EDX、TEM和XRD表征.研究了H₂PtCl₆乙二醇溶液的pH值对微波合成铂纳米粒子的大小、均匀性及其在碳载体上分散程度的影响.研究结果发现对于Pt/XC-72碳,随着pH值从3.4增加到9.5,铂纳米粒子的平均粒径从5.5nm减小到2.7nm;对于Pt/CNTs,随着pH值从3.5增加到9.4,铂纳米粒子的平均粒径从5.3nm减小到2.8nm.另外,随着pH值的增加,铂纳米粒子的尺寸均匀性及其在碳载体表面的分散程度得到改善.     

Effect of Co and Ni nanoparticles formation on carbon nanotubes growth via PECVD

The effect of cobalt (Co) and nickel (Ni) nanoparticle catalysts on the growth of carbon nanotubes (CNTs) were studied, where the CNTs were vertically grown by plasma enhanced chemical vapour deposition (PECVD) method. The growth conditions were fixed at a temperature of 700 °C with a pressure of 1000 mTorr for 40 minutes with various thicknesses of sputtered metal catalysts. Only multi-walled carbon nanotubes are present from the growth as large average diameter of outer tube (～10–30 nm) were measured for both of the catalysts used. Experimental results show that high density of CNTs was observed especially towards thicker catalysts layers where larger and thicker nanotubes were formed. The nucleation of the catalyst with various thicknesses was also studied as the absorption of the carbon feedstock is dependent on the initial size of the catalyst island. The average diameter of particle size increases from 4 to 10 nm for Co and Ni catalysts. A linear relationship is shown between the nanoparticle size and the diameter of tubes with catalyst thicknesses for both catalysts. The average growth rate of Co catalyst is about 1.5 times higher than Ni catalyst, which indicates that Co catalyst has a better role in growing CNTs with thinner catalyst layer. It is found that Co yields higher growth rate, bigger diameter of nanotube and thicker wall as compared to Ni catalyst. However, variation in Co and Ni catalysts thicknesses did not influence the quality of CNTs grown, as only minor variation in I_G/I_D ratio from Raman spectra analysis. The study reveals that the catalysts thickness strongly affects not only nanotube diameter and growth rate but also morphology of the nanoparticles formed during the process without influencing the quality of CNTs.