Chair of Organic Chemistry II , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Henkestrasse 42 , 91054 Erlangen , Germany.
Joint Institute of Advanced Materials and Processes , Friedrich-Alexander-Universität Erlangen-Nürnberg , Dr.-Mack-Strasse 81 , 90762 Fürth , Germany.
J Am Chem Soc. 2018 Mar 7;140(9):3352-3360. doi: 10.1021/jacs.7b12910. Epub 2018 Feb 21.
Single-walled carbon nanotubes (SWCNT) have been covalently cross-linked via a reductive functionalization pathway, utilizing negatively charged carbon nanotubides (KC). We have compared the use of difunctional linkers acting as molecular pillars between the nanotubes, namely, p-diiodobenzene, p-diiodobiphenyl, benzene-4,4'-bis(diazonium), and 1,1'-biphenyl-4,4'-bis(diazonium) salts as electrophiles. We have employed statistical Raman spectroscopy (SRS), a forefront characterization tool consisting of thermogravimetric analysis coupled with gas chromatography and mass spectrometry (TG-GC-MS) and aberration-corrected high-resolution transmission electron microscopy imaging series at 80 kV to unambiguously demonstrate the covalent binding of the molecular linkers. The present study shows that the SWCNT functionalization using iodide derivatives leads to the best results in terms of bulk functionalization homogeneity ( H) and degree of addition. Phenylene linkers yield the highest degree of functionalization, whereas biphenylene units induce a higher surface area with an increase in the thermal stability and an improved electrochemical performance in the oxygen reduction reaction (ORR). This work illustrates the importance of molecular engineering in the design of novel functional materials and provides important insights into the understanding of basic principles of reductive cross-linking of carbon nanotubes.
单壁碳纳米管（SWCNT）通过还原功能化途径进行了共价交联，利用带负电荷的碳纳米管（KC）。我们比较了二官能团连接体作为纳米管之间的分子支柱的用途，即对二碘苯、对二碘联苯、苯-4,4'-二重氮、和 1,1'-联苯-4,4'-二重氮盐作为亲电试剂。我们采用了统计拉曼光谱（SRS），这是一种前沿的表征工具，包括热重分析与气相色谱和质谱（TG-GC-MS）以及在 80 kV 下的像差校正高分辨率透射电子显微镜成像系列，以明确证明了分子连接体的共价结合。本研究表明，使用碘化物衍生物对 SWCNT 进行功能化，在整体功能化均匀性（H）和添加程度方面可以得到最佳结果。亚苯基连接体产生了最高的功能化程度，而联苯单元则增加了表面积，同时提高了热稳定性和在氧还原反应（ORR）中的电化学性能。这项工作说明了分子工程在设计新型功能材料中的重要性，并为理解碳纳米管还原交联的基本原理提供了重要的见解。
