活性炭上化学气相沉积法生长纳米碳纤维

利用流化床技术,以天然气为碳源,负载于活性炭上的纳米镍粒子为催化剂,在750 ℃下采用化学气相沉积法制备了气相生长纳米碳纤维(VGCNFs)/活性炭(AC)复合物。通过对样品进行XRD、激光拉曼光谱、扫描电镜和氮吸附检测,发现VGCNFs生长在活性炭的各个侧面上,以顶部生长模式为主,纤维的直径在40～120 nm之间,由于粗糙的纤维表面和石墨片层的翘曲而缺陷较多。VGCNFs/AC复合物与原料活性炭相比,BET比表面积从2 367 m²·g^-1降到了1 474     

固体单相催化剂CVD法制备成束或分散MWCNT

CVD法制备纳米碳管的催化剂多是以Al2O3、SiO2或MgO作载体,Fe、 Ni或Co等过渡族金属为活性组分[1-3].     

减压化学气相沉积法制备规则螺旋状纳米碳管

以硅胶负载的Co纳米颗粒为催化剂,在低流量的减压体系中通过化学气相沉积法制备了规则螺旋状的纳米碳管.通过TEM和HRTEM研究了螺旋碳管的形貌、尺度分布以及管身、曲面和节点处的晶型;讨论了催化剂制备中pH值对催化剂的尺寸、规则程度和存在形态以致对螺旋碳管产量、管径厚度以及螺旋管的相对比例的影响;此外,还分析了反应压力对碳管生长的影响.     

微波等离子体化学气相沉积法低温制备直纳米碳管膜

Among the three main methods for the synthesis of carbon nanotubes (CNTs)， chemical vapor deposition (CVD) has received a great deal of attention since CNTs can be synthesized at significantly low temperature. Plasma chemical vapor deposition methods can synthesize CNTs at lower temperature than thermal CVD. But in the usual catalytic growth of CNTs by CVD， CNTs are often tangled together and have some defects. These will limit the property research and potential applications. How to synthesize the straight CNTs at low temperature becomes a challenging issue. In this letter， straight carbon nanotube (CNT) films were achieved by microwave plasma chemical vapor deposition (MWPCVD) catalyzed by round Fe-Co-Ni alloy particles on Ni substrate at 610℃. It was found that， in our experimental condition， the uniform growth rate along the circumference of round alloy particles plays a very important role in the growth of straight CNT films. And because the substrate is conducting， the straight CNT films grown at low temperature may have the benefit for property research and offer the possibility to use them in the future applications.     

纳米碳管电极的制备与电化学检测性能研究

纳米碳管由于其独特的物理和化学性能及广阔的应用前景而备受关注,其相关研究涉及到众多领域[1￣3]。在电化学分析领域,与其它碳电极材料相比,纳米碳管电极具有较大的电极表面积和较高的电子传递速率,其使用能增大响应电流、降低检出限,是目前电化学分析电极中一个十分引人注目     

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.     

MWPCVD低温合成纳米碳管的生长机理

The synthesis of carbon nanotubes (CNTs) at low temperature has received a great deal of attention and be-comes a challenging issue. But few model which accounts for the growth of CNTs is suited for the synthesis of CNTs by microwave plasma chemical vapor deposition (MWPCVD) at low temperature because most researchers conclude that the growth mechanism is determined by the catalyst-supporter interaction while ignored the diffusion of carbon in the catalyst. In this paper, under the catalytic effect of cobalt supported by SiO₂ and Al₂O₃, CNTs are synthe-sized by MWPCVD at about 500℃, and tip-growth, the model which accounts for the catalytic growth of CNTs is outlined. It is the temperature difference between the upper and bottom of the catalytic particle that results in the diffusion of carbon atoms from upper to the bottom, and precipitation of saturated carbon on the bottom surface to form CNTs.     

NaCl担载Fe催化裂解乙炔制备纳米碳材料

以水溶性NaCl担载Fe作催化剂,于400℃和420C下化学气相沉积法催化裂解乙炔进行了反应.通过X射线衍射仪、扫描电子显微镜和能谱分析仪对催化剂进行了表征,表征结果显示:活性组分Fe被分散成了粒径在10～40nm之间的纳米颗粒;通过扫描电子显微镜和高分辨透射电镜对产物进行了表征,表征结果显示:当裂解温度为400℃时,...     

玻璃基片上纳米碳管电极的集成

利用微波等离子体化学气相沉积法在玻璃孔穴中定位生长纳米碳管电极, 分析了负偏压对纳米碳管电极生长的影响. 该电极对铜离子的电化学检测性能分析结果表明, 所制备的纳米碳管电极具有良好的电化学检测性能, 位于－0.0100 V附近的铜离子的还原峰峰形良好, 其电流在铜离子浓度为0.01~0.30 mmol•L^-1时, 与Cu²⁺浓度呈良好的线性关系, 相关系数为0.9975, 且具有较好的长期稳定性和重现性.     

Purification of Single-walled Carbon Nanotubes Grown by a Chemical Vapour Deposition (CVD) Method

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｇｌｅ ｗａｌｌｅｄｃａｒｂｏｎｎａｎｏｔｕｂｅｓ(ＳＷＮＴｓ)ｈａｖｅｂｅｅｎｓｙｎｔｈｅｓｉｓｅｄｂｙｕｓｉｎｇｖａｒｉｏｕｓｍｅｔｈｏｄｓ[1— 3] ａｎｄｔｈｅｃｈｅｍｉｃａｌｖａｐｏｕｒｄｅｐｏｓｉｔｉｏｎ (ＣＶＤ )ｍｅｔｈｏｄｈａｓｂｅｅｎｃｏｎｓｉｄｅｒｅｄａｓａ ｐｒｏｍｉｓｉｎｇｍｅｔｈｏｄｔｏ ｐｒｏｄｕｃｅＳＷＮＴｓｏｎａｎｉｎｄｕｓｔｒｉａｌｓｃａｌｅ[3— 5] .Ｈｏｗｅｖｅｒ ,ａｌｌｔｈｅＳＷＮＴ ｐｒｏｄｕｃｔｓｓｙｎｔｈｅｓｉｓｅｄｔｏｄａｔｅｃｏ…     

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.     

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)。     

甲烷在流态化催化剂床裂解生长多壁碳纳米管

甲烷在流态化催化剂床裂解生长多壁碳纳米管;多壁碳纳米管;Ni-Mg-O催化剂;甲烷;流化床;催化化学蒸汽沉积法     

MgO负载Fe基催化剂选择性合成单/双/多壁碳纳米管

通过浸渍及水热处理获得MgO负载的Fe基催化剂,并将其用于化学气相沉积过程裂解甲烷获得碳纳米管.结果表明,单/双/多壁碳纳米管可选择性地生长在Fe负载量不同的Fe/MgO催化剂上.当Fe负载量仅为0.5%时,铁原子在载体表面烧结为0.8～1.2nm的铁颗粒,碳在这种小颗粒上以表面扩散为主,导致单壁碳纳米管形成,并且单壁碳纳米管的选择性高达90%.当Fe负载量提高到3%时,铁原子聚集成约2.0nm的颗粒,在化学气相沉积中生长碳纳米管时,碳在Fe催化剂颗粒中的体相扩散的贡献增大,在表相扩散和体相扩散的共同作用下,双壁碳纳米管的选择性显著增高.当进一步增加Fe负载量时,铁原子烧结形成1～8nm的颗粒,经过化学气相沉积,在催化剂上生长了单、双、多壁碳纳米管.随着Fe在MgO载体上负载量的增加,管径、管壁数以及半导体管的含量都增加.本研究提供了一种适合大批量选择性生长单/双/多壁碳纳米管的方法.     

Carbon Nanotubes Grown on Sepiolite as Catalyst Carrier

Multi-walled carbon nanotubes were synthesized by the catalytic decomposition of acetylene at 750℃ over sepiolite powder,which was treated with aqueous cobalt nitrate. It is expected that the composite with high specific area will have high capacity of hydrogen storage.     

催化剂活性组分及温度对化学气相沉积法制备碳纳米管的影响

通过XRD、DTA和TEM方法 ,研究了不同温度下催化剂活性组分Co和Ni对化学气相沉积(CVD)法制备碳纳米管的影响。结果表明 ,在最佳反应温度 ( 65 0℃ )下 ,碳纳米管在催化剂Co Al2 O3 上的产率为 45 7g 1 0 0g·cat,高于在Ni Al2 O3 上的产率 3 42g 1 0 0g·cat。XRD分析表明 ,相对于催化剂Co Al2 O3 ,在Ni Al2 O3 上制备的碳纳米管石墨化程度更高。当合成温度从 65 0℃增加到 75 0℃时 ,在催化剂Co Al2 O3 和Ni Al2 O3 上生成的多壁碳纳米管的 ( 0 0 2 )晶面的层间距分别从 3 45 和 3 42 减小到 3 3 9 和3 3 7 。进一步分析发现 ,在焙烧或催化反应过程中 ,Co、Ni与γ Al2 O3 之间存在相互作用且生成了新相物质 ,其衍射峰分别为 2θ=5 1 5 6°和 2θ=5 1 97°     

A Nitric Oxide Biosensor Based on Myoglobin Adsorbed on Multi‐Walled Carbon Nanotubes

Myoglobin (Myb) of horse heart is incorporated on multi‐walled carbon nanotubes (MWNTs) and immobilized at a glassy carbon (GC) electrode surface. Its electrochemical behavior and enzyme activity are characterized by employing electrochemical methods. The results indicate that MWNTs can obviously promote the direct electron transfer between Myb and electrode, and that the Myb on MWNTs behaves as an enzyme‐like activity towards the electrochemical reduction of nitric oxide (NO). Accordingly, an unmediated NO biosensor is constructed. Experimental results reveal that the peak current related to NO is linearly proportional to its concentration in the range of 2.0×10^?7–4.0×10^?5 mol/L. The detection limit is estimated to be 8.0×10^?8 mol/L. Considering a relative standard deviation of 2.1% in seven independent determinations of 1.0×10^?5 mol/L NO, this biosensor shows a good reproducibility. The biosensor based on Myb/MWNTs modified electrode can be used for the rapid determination of trace NO in aqueous solution with a good stability, nice selectivity and easy construction.