物理化学学报

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FeCo/MgO催化生长体相单壁碳纳米管的直径调控

张则尧1,2,4,5, 姚艺希2,3, 李彦2,3,4   

  1. 1 北京大学深圳研究院, 广东 深圳 518057;
    2 北京分子科学国家研究中心, 纳米器件物理与化学教育部重点实验室, 稀土材料化学及应用国家重点实验室, 北京大学化学与分子工程学院, 北京 100871;
    3 北京大学前沿交叉学院, 北京 100871;
    4 深港产学研基地, 广东 深圳 518057;
    5 北京大学工学院, 北京 100871
  • 收稿日期:2021-01-28 修回日期:2021-03-02 录用日期:2021-03-02 发布日期:2021-03-04
  • 通讯作者: 李彦 E-mail:yanli@pku.edu.cn
  • 基金资助:
    深圳市科技计划项目(JCYJ20170817113121505), 深圳市海外高层次人才创新创业专项资金(KQTD20180411143400981), 科技部国家科技重大专项(2016YFA0201904), 国家自然科学基金(21631002)及北京分子科学国家研究中心(BNLMS-CXTD-202001)资助

Modulating the Diameter of Bulk Single-Walled Carbon Nanotubes Grown by FeCo/MgO Catalyst

Zeyao Zhang1,2,4,5, Yixi Yao2,3, Yan Li2,3,4   

  1. 1 Peking University Shenzhen Institute, Shenzhen 518057, Guangdong Province, China;
    2 Beijing National Laboratory for Molecular Science, Key Laboratory for the Physics and Chemistry of Nanodevices, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China;
    3 Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China;
    4 PKU-HKUST ShenZhen-HongKong Institution, Shenzhen 518057, Guangdong Province, China;
    5 College of Engineering, Peking University, Beijing 100871, China
  • Received:2021-01-28 Revised:2021-03-02 Accepted:2021-03-02 Published:2021-03-04
  • Contact: Yan Li E-mail:yanli@pku.edu.cn
  • Supported by:
    The project was supported by the Shenzhen Basic Research Project (JCYJ20170817113121505), the Shenzhen KQTD Project (KQTD20180411143400981), the National Science and Technology Major Project of the Ministry of Science and Technology of China (2016YFA0201904), the National Natural Science Foundation of China (21631002), and the Beijing National Laboratory for Molecular Sciences (BNLMS-CXTD-202001).

摘要: 单壁碳纳米管的直径可控生长是碳纳米管生长与应用领域的重要问题。直径在0.9–1.2 nm范围内的碳纳米管非常适合应用于近红外荧光生物成像领域和量子器件单光子光源之中。本文使用FeCo/MgO催化剂生长出了直径在这一范围内的体相单壁碳纳米管,并研究了催化剂制备和CVD生长条件对碳纳米管直径的影响。催化剂前驱体的制备是获得小尺寸催化剂颗粒的关键步骤。在浸渍过程中,使用难水解的金属硫酸盐作为前驱体、降低浸渍pH以及加入络合剂分子都会抑制溶液干燥过程中金属盐的水解,从而控制催化剂的尺寸,使其适合于生长出直径可控的单壁碳纳米管。在CVD生长过程中,使用乙醇作为碳源、使用较低的碳氢比例也有利于小直径碳纳米管的生长。

关键词: 单壁碳纳米管, 化学气相沉积, 可控生长, 直径, 金属催化剂, 前驱体, 纳米颗粒

Abstract: The diameter-controlled growth of single-walled carbon nanotubes (SWNTs) is one of the key issues of SWNT synthesis and application. To guarantee that SWNTs grow with desired diameters, it is necessary to control catalyst size and modulate growth conditions. SWNTs with diameters of 0.9–1.2 nm are highly desirable for near-infrared fluorescence bioimaging and serving as effective single-photon sources for the development of quantum devices. Herein, we used an FeCo/MgO catalyst to grow bulk SWNTs with diameters in the range and studied the influence of catalysts and chemical vapor deposition (CVD) growth conditions on the diameter of SWNTs. The preparation of catalyst precursors is a key step in obtaining catalyst nanoparticles of small size. In the impregnation process, we used three different types of metal salts, namely, sulfates, acetates, and nitrates, to prepare the catalysts. The metal sulfates, which exhibit the weakest hydrolysis ability, were found to grow SWNTs with the smallest diameters. Lowering the immersion pH, which suppresses the hydrolysis of metal ions, was also favorable for growing smaller SWNTs. Moreover, the addition of complexing agent molecules such as ethylenediaminetetraacetic acid during the impregnation process, which inhibits the hydrolysis of metal ions as well, further confined the diameter distribution of the resultant SWNTs. During the solution drying process, metal salts hydrolyze into metal hydroxides and oxides. Under mild hydrolysis conditions, the produced hydroxide and oxide particles are smaller and more likely to be uniformly distributed on the surface of the supports. Therefore, it is more favorable to produce catalysts with controlled sizes under mild hydrolysis conditions, which are preferred for diameter control of the resultant SWNTs. In the CVD growth process, we used either ethanol or methane as the carbon source and found that, under our experimental conditions, the SWNTs grown from ethanol had smaller diameters than those from methane. The hydrogen content in the CVD process also affects diameter distribution of SWNTs. As the carbon-to-hydrogen ratio decreased, SWNTs with larger diameters disappeared, and the number of SWNTs with smaller diameters increased. During the CVD process, the carbon-to-hydrogen ratio determines the carbon feeding rate to the catalysts. At a low carbon feeding rate, catalysts of large sizes are underfed and unable to grow SWNTs, whereas smaller catalysts are in a favorable condition for growth. Therefore, the average diameter of the SWNTs decreased as the carbon-to-hydrogen ratio decreased.

Key words: Single-walled carbon nanotube, Chemical vapor deposition, Controlled growth, Diameter, Metal catalyst, Precursor, Nano particle

MSC2000: 

  • O643