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。     

氮掺杂长竹节状碳纳米管的制备及其生长机理

本文采用电弧放电法,通过阳极棒与不锈钢片的共蒸发,制备了氮掺杂长竹节状碳纳米管。借助扫描电子显微镜（SEM）、场发射高分辨透射电子显微镜（HRTEM）及其附带能量色散X射线（EDX）光谱仪和电子能量损失谱（EELS）、透射电子显微镜（TEM）等表征方法,对产物的形貌、结构和组成进行表征。表征结果表明,氮掺杂长竹节状碳纳米管的长度在640~835nm之间,其内径在23~35nm之间,外径在28~47nm之间;且在每一节“竹节”与另一节“竹节”的连接处形成的内腔中均有一个黑色纳米颗粒,其直径尺寸以及产物中的氮掺杂长竹节状碳纳米管的含量均与熔化、蒸发的不锈钢片的面积有关。本文还对氮掺杂长竹节状碳纳米管的生长机理进行了简单的探讨。     

氮掺杂竹节状碳纳米管的催化合成

以有机胺为碳和氮源, 用催化方法合成出了含氮大管径竹节状碳纳米管. Fe/SBA-15分子筛为催化剂, 有机胺经过973 K高温裂解得到氮掺杂竹节状碳纳米管材料(CN_X). 比较了铁含量、二乙胺和六次甲基四胺原料对合成氮掺杂碳纳米管形貌和氮掺杂量的影响; 合成出氮碳比(N/C原子比)为0.26的氮掺杂竹节状碳纳米管材料.     

含氮竹节状碳纳米管的催化合成

以二乙胺为原料，用催化方法合成出了含氮大管径竹节状碳纳米管，以含铁 SAPO-5分子筛为催化剂，二乙胺经过1073K高温裂解得到的碳纳米管材料，其内径 约60nm,壁厚为6nm，并且成竹节状。它有较高的表面和较高的氮碳比。     

溶剂热法合成碳纳米材料

本文综述了溶剂热法合成多种碳纳米管、纳米电缆、纳米棒、纳米球和纳米空心锥的研究现状。350 ℃下用金属钾还原六氯代苯,在用不同催化剂时,可分别得到碳纳米管和碳球,碳球的形成可以解释为石墨层的微条卷曲而成。600 ℃下金属镁还原乙醇得到了竹节状和Y-型碳纳米管。500 ℃下还原四氯化碳和碳酸钠可得到平均直径为100 nm的碳纳米管。700 ℃下金属锌还原乙醚制成了左右螺旋型交织的碳纳米管。在硫的存在下,200 ℃以下二茂铁热解成非晶碳纳米管和Fe/非晶碳纳米同轴电缆。     

氮掺杂长竹节状碳纳米管的制备及其生长机理

采用电弧放电法,通过阳极棒与不锈钢片的共蒸发,制备了氮掺杂长竹节状碳纳米管(NDLBLCNTs)。借助扫描电子显微镜(SEM)、场发射高分辨透射电子显微镜(HRTEM)及其附带能量色散X射线(EDX)光谱仪和电子能量损失谱(EELS)、透射电子显微镜(TEM)等表征方法,对产物的形貌、结构和组成进行表征。表征结果表明,NDLBLCNTs的长度在640~835 nm之间,其内径在23~35 nm之间,外径在28~47 nm之间;且在每一节"竹节"与另一节"竹节"的连接处形成的内腔中均有一个黑色纳米颗粒,其直径尺寸以及产物中的NDLBLCNTs的含量均与熔化、蒸发的不锈钢片的面积有关。对NDLBLCNTs的生长机理进行了简单的探讨。     

氮掺杂碳纳米管负载的钌催化剂对苯甲醇在常压空气条件下催化氧化性能

以氮掺杂碳纳米管(NCNTs)为载体,采用乙二醇微波还原方法方便制得制备了负载型Ru催化剂,Ru纳米颗粒均匀分散在NCNTs表面,平均粒径为1.6 nm。在温和条件下(常压和空气条件),Ru/NCNTs催化剂表现出良好的苯甲醇催化氧化性能,在90℃下苯甲醇转化率可达93%,苯甲醛选择性大于99%,并且具有良好的可重复使用性能,这些结果显著优于碳纳米管(CNTs)和活性炭(AC)为载体的对比组催化剂。在温和条件下Ru/NCNTs催化剂表现出的优异苯甲醇催化氧化性能可归因于氮掺杂提高了NCNTs的电子密度进而促进了O2分子吸附和反应。     

以吡啶为原料制备氮掺杂碳纳米管

在700～800 ℃,以吡啶为原料用CVD方法制备出了管径在20～40 nm的竹节状碳纳米管. EDX和XPS结果都表明氮掺杂到碳纳米管中. HRTEM研究发现掺氮碳纳米管的竹节由数层石墨片弯曲而成,纳米管外层石墨层逐渐消失.从Raman谱图的对照中发现,与相似条件下制备出的纯碳纳米管相比,氮掺杂碳纳米管的D谱带对G谱带的相对强度增加, TGA研究发现掺杂纳米管在较低温度下即被氧化,这些结果都说明氮掺杂使得纳米管的缺陷增加.     

催化剂载体对CVD法制备碳纳米管的影响

用DTA、TEM和XRD方法研究了碳氢化合物催化裂解制备碳纳米管(CNTs)反应中催化剂载体的影响。实验结果表明:当以金属Co作为活性组分时,对于催化剂Co/Al₂O₃,在最佳反应温度(650℃)条件下,碳纳米管粗产品的产率为457g/100g·cat,明显高于以Co/SiO₂作载体时的产率131g/100g·cat,且碳纳米管直径小,直径分布范围窄(10nm～20nm)。但在空气气氛中的DTA结果表明,在催化剂Co/SiO₂上生成的碳纳米管的抗氧化能力较在催化剂Co/Al₂O₃上生成的碳纳米管强。通过TEM和XRD方法进一步研究发现:反应过程中,催化剂Co/Al₂O₃中的Co微晶粒度随反应温度升高(从650℃到750℃)而增大(从15.8nm到16.7nm)的速率小于催化剂Co/SiO₂中的Co微晶粒度随反应温度升高而增大(从11.0nm到13.4nm)的速率;相应地,在催化剂Co/Al₂O₃上生成的碳纳米管的(外)直径随反应温度升高而增大的速率(从10～20nm到20～25nm)亦小于在催化剂Co/SiO₂上生成的碳纳米管的(外)直径随反应温度升高而增大的速率(从10～30nm到30～50nm)。     

低压下酞菁裂解法制备定向碳纳米管阵列

在低压条件下以酞菁铁为原料, 采用独立双温控加热系统在石英玻璃基底上气相沉积制备了大面积准直性好和管径均匀的碳纳米管. 利用扫描电子显微镜(SEM/FESEM)和透射电子显微镜(TEM)研究了定向碳纳米管的生长形态和结构. 详细讨论了系统真空度、反应温度、气体流速及氢气和氩气的体积比例等参数对碳纳米管生长的影响, 并测试了该碳纳米管的场发射性能及超电容性能.     

直立碳纳米管超级电容器的研究

在石英玻璃基底上,以酞菁裂解法低压气相沉积制备大面积管径均匀、长度一致的直立碳纳米管.分别应用电解质溶液浸润、酸处理和循环伏安扫描等3种不同方法纯化活化该直立碳纳米管,并以活化后的碳纳米管作为原型超级电容器的电极.循环伏安扫描和交流阻抗测试表明,CV曲线呈近似矩形,交流阻抗最大相位角超过80°,该直立碳纳米管的比电容为16~32F/g,乃超级电容器理想的电极材料.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin on Aligned Carbon Nanotubes Based Electrodes Modified with Au Nanoparticles and SiO2 Gel

Here we report on the preparation and characterization of new electrodes based on aligned carbon nanotubes (ACNTs) for hemoglobin (Hb) electrochemistry and electrocatalysis. The ACNTs are obtained by a thermal chemical vapor deposition method under normal pressure. Then the electrodes are elaborated by first sputtering a thin Au film (thickness of 200 nm) onto the top of the ACNTs, and then removing the Au layer/ACNTs from the quartz substrate with the aide of hydrofluoric acid (HF) treatment. Field emission scanning electron microscopy (FESEM) demonstrates that after nitric acid (HNO₃) treatment, the nanotubes of the removed Au layer are totally tip‐opened, purified and organized in a perfect vertically aligned architecture. The final ACNTs electrode is obtained by attaching the Au layer of ACNTs onto a glassy carbon electrode. Then the electrode was modified to act as a matrix for hemoglobin (Hb) immobilization and as an electrode for Hb electroanalysis by the assistance of Au nanoparticles (AuNPs) and SiO₂ gel. Due to the individual specific effects of AuNPs, SiO₂ gel and ACNTs, the resulting SiO₂/Hb‐AuNPs/ACNTs electrode showed good direct electrochemistry of Hb with an apparent Michaelis? Menten constant of 0.44 mM. The electrode showed an excellent electrocatalytic activity towards H₂O₂, possessing a linear range from 40 µM to 4 mM and the detection limit was 22 µM based on a signal to noise ratio of 3.     

活化条件对活性碳纳米管比表面积的影响

以KOH为活化剂, 研究了多壁碳纳米管在制备活性碳纳米管过程中四个重要影响因素: 活化剂用量、活化温度、活化时间和活化过程中保护气体的流速对所得活性碳纳米管BET比表面积的影响并解释了原因. 研究表明上述四个因素都会对活性碳纳米管的比表面积产生较大的影响, 其中活化剂用量的影响最大, 在研究范围内可引起比表面积增大约241 m²•g^-1. 在这四个影响因素中除活性碳纳米管的比表面积随活化温度的增加而不断增加外, 其他三个影响因素的变化都会使活性碳纳米管的比表面积出现最大值, 而且四个影响因素的改变, 都不改变活性碳纳米管的孔洞主要是中孔和大孔的特点.     

Bamboo-shaped carbon tubes from coal

Bamboo-shaped carbon tubes (BCTs) were first synthesized in high yields from iron-loaded carbon electrodes prepared from coal by arc discharge. The BCTs were characterized by scanning electron microscopy and transmission electron microscopy (TEM). The TEM characterization reveals that the tubes have bamboo-like structures consisting of hollow compartments separated with conical shaped graphite layers. The diameters of BCTs are in the range of 40–60 nm with their length being about several micrometers. For some BCTs, the hollow compartments are quite uniform with a size of 100 nm. A growth model is suggested to explain the formation of bamboo structure in tubes.     

Application of Thermogravimetry and Differential Thermal Analysis in Catalytic CVD Synthesis of Carbon Nanotubes

Multi-walled carbon nanotubes (MW-CNTs) were prepared by chemical vapor deposition (CVD) method with the decomposition of acetylene over Co/SiO2 catalyst. TG-DTA technique was used together with TEM and XRD to study the effect of reaction temperature on the composition, graphitized extent, and diameter distribution of the produced raw CNTs based on their oxidization resistance. During the decomposition, the micro-crystallite of the active constituent (Co/SiO2) were growing up as the reaction temperature rising. This in turn resulted in an increase of the diameter distribution range of produced MW-CNTs. The average diameter increased from 20~30 nm (650℃) to 30~50 nm (750℃). XRD results also showed the graphitized extent of MW-CNTs was enhanced meanwhile the spacing between the layers (d002) decreased from 3.45 (650℃) to 3.32 (850℃) with the reaction temperature raised. TG-DTA data showed that the exothermic peak of the amorphous carbon was below 380℃and its content would decrease as temperature increasing. In summary, for CVD production of CNTs using acetylene gas on Co/SiO2 catalyst, low temperature (about 650℃) favored producing thinner MW-CNTs with the diameter from 20 to 30 nm while higher temperature (about 850℃) is favored thicker MW-CNTs (diameter from 70 to 100 nm).     

酞菁裂解法多壁碳纳米管的制备、表征和应用

In order to investigate the catalytic activity of high temperature treated CoPc toward oxygen reduction, and find the active site of the catalyst, using cobalt (Ⅱ) phthalocyanine (CoPc) as raw material, through thermal chemical vapor deposition method at 850℃ under a current of Ar/H2, two layer well-aligned multiwalled carbon nanotubes (CNTs) were made. The diameters of the well-aligned carbon nanotubes were distributed in the range of 60～120 nm and the length was about 40 μm. The Co particle with 10 nm in diameter was encapsulated in the CNTs compartment. The products were observed by field emission scanning electron microscope (SEM), and transmission electron microscope (TEM). The well-aligned carbon nanotubes were characteriszed by Raman scattering spectrum and X-ray diffraction (XRD). The cyclic voltammetric measurement demonstrates that the CNTs have some effect to prevent the metal nanoparticle encapsulated from eroding rapidly. It is assumed that the small amount of the N element in the CNTs is very necessary for the bamboo-like morphology and the protected action for metal particles against dissolution in the acid medium. The radian of the winding wall should be affected by the amount of the N and the interaction between the N in the carbon network and the metal cluster. In addition, the CNTs greater electrochemically active surface area is a great advantage for any electrocatalytic application.     

Synthesis of mesoporous silica nanobamboo with highly dispersed tungsten carbide nanoparticles

By controlling the interaction between cationic surfactant micelles and ammonium metatungstate during the formation of mesoporous silica structure, highly dispersed tungsten carbide (WC) nanoparticles of 2.0 nm in diameter on mesoporous silica nanospheres were synthesized at lower concentration of ammonium metatungstate. With additional ammonium metatungstate, a novel mesoporous silica nanobamboo structure was formed with bimodal size-distributed WC nanoparticles, in which 2.0 nm WC was homogeneously distributed in nanobamboo's mesoporous silica wall and those with larger diameter (10.0-20.0 nm) were only formed on the nanobamboo's inner surface and at its internodes. The mesoporous silica nanobamboo also had a very high tensile strength due to its bamboo-like structure.     

利用ＳＢＡ-１５介孔内纳米碳合成含介孔的ＺＳＭ-５分子筛

SBA-15介孔分子筛内填充蔗糖并炭化后, 分别在碱性和弱酸性条件下, 用含铝源及TPABr的溶液浸渍,将SBA-15分子筛孔壁的无定形结构转化成ZSM-5分子筛的晶体结构, 除碳后得到含介孔的ZSM-5分子筛. 用X射线衍射、 N_2吸附-脱附、 ~(27)Al MAS NMR、 NH_3-TPD、 TEM、 SEM等对样品进行了表征, 考察了晶化时间等参数对样品的影响. 结果表明, 碱性条件下合成的ZSM-5分子筛晶体中含有少量孔径约3.2～4.2 nm的介孔孔道, 其酸强度接近与常规ZSM-5分子筛的酸强度;弱酸性条件下合成的ZSM-5分子筛晶体中含有大量孔径约1.4～1.6 nm的孔道, 其酸强度明显低于常规ZSM-5分子筛的酸强度.     

铂纳米颗粒修饰直立碳纳米管电极的葡萄糖生物传感器

基于Pt纳米颗粒修饰直立的碳纳米管电极制备了葡萄糖生物传感器.铂纳米颗粒是利用电位脉冲沉积法修饰到直立碳纳米管上的,可以增强电极对酶反应过程当中产生的过氧化氢的催化行为.用扫描电镜和透射电镜观察了直立碳纳米管在修饰Pt纳米颗粒前后的形态.该酶电极对葡萄糖的氧化表现出很好的响应,线性范围为1×10-5～7×10-3mol/L,响应时间小于5s,并且有很好的重现性.