Carbon nanotubes (CNTs) are considered promising for a large range of emerging technologies ranging from advanced electronics to utilization as nanoreactors. Here we report a controlled facile synthesis of aligned carbon nanotubes with very small dimensions directly grown on steel grid substrates via two-step catalytic chemical vapor deposition (CCVD) of a molecular catalyst (ferrocene) with ethylene as the carbon source. The system is characterized by resonance Raman spectroscopy and the results show single walled carbon nanotube (SWCNT) arrays composed of 0.80 nm to 1.24 nm semiconducting CNTs, as analyzed using Kataura analysis, which is approaching the lowest diameters attainable for SWCNTs. The G⁺ and G⁻ mode splitting, G⁻ line shapes and ring breathing modes (RBMs) are analyzed to characterize the CNTs. The approach results in close packed and vertically aligned SWCNT bundles formed into hair shapes, with some contribution from multiwall CNTs (MWCNTs). IR spectroscopy is utilized to characterize the edge/defect states that have the ability to form esters and ether bonds in the as-prepared CNTs. The stepwise deposition of the catalyst followed by the carbon source gives control over the formation of small diameter single walled carbon nanotubes (SWCNTs). The utilization of molecular catalysts for narrow diameter growth directly on steel grid substrates forms a promising approach for producing cost-effective CNT substrates for a plethora of sensing and catalytic applications.

中文翻译：

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用分子催化剂在钢基底上制备直径非常窄的定向碳纳米管阵列的共振拉曼光谱和红外光谱

碳纳米管（CNT）被认为可用于从新兴电子技术到用作纳米反应器的各种新兴技术。在这里，我们报告了一种可控制的，易于合成的，尺寸很小的定向碳纳米管，它通过使用乙烯作为碳源的分子催化剂（二茂铁）的两步催化化学气相沉积（CCVD）直接生长在钢格架基板上。该系统的特征在于共振拉曼光谱，结果显示，如Kataura分析所分析，由0.80 nm至1.24 nm的CNT组成的单壁碳纳米管（SWCNT）阵列接近SWCNT所能达到的最小直径。对于g ⁺和G ^-模分裂，G ^-分析线形和环形呼吸模式（RBM）以表征CNT。该方法导致紧密堆积且垂直对齐的SWCNT束形成头发形状，其中多壁CNT（MWCNT）有所贡献。利用红外光谱来表征边缘/缺陷状态，该边缘/缺陷状态具有在所制备的CNT中形成酯和醚键的能力。催化剂的逐步沉积以及随后的碳源可以控制小直径单壁碳纳米管（SWCNT）的形成。利用分子催化剂直接在钢格架基板上进行窄直径生长，形成了一种有前途的方法，可用于生产具有成本效益的，用于多种传感和催化应用的CNT基板。