Duraia El-Shazly M, Opoku Mikael, Beall Gary W
Physics Department, Faculty of Science, Suez Canal University, Ismailia, 41522, Egypt.
Department of Chemistry and Biochemistry, Texas State University-San Marcos, 601 University Dr., San Marcos, TX, 78666, USA.
Sci Rep. 2024 Jul 16;14(1):16405. doi: 10.1038/s41598-024-65893-6.
The present work reports the synthesis of multi-wall carbon nanotubes (MWCNTs) over graphite nanosheets by an easy and simple approach without using any external catalyst. Simply, yellow corn seeds were thermally annealed in a hydrogen atmosphere at 1050 °C for 3 h without any pretreatments. Notably, the growth of MWCNTs was observed to preferentially occur on the outer surface of the corn shell. This uncomplicated approach not only emphasizes the feasibility of synthesizing carbon nanomaterials using agricultural by-products but also underscores the potential applications of these synthesized materials in various fields. Samples were examined through a comprehensive analysis employing various techniques, including scanning electron microscopy (SEM), Raman spectroscopy, FTIR, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). The findings unveiled the formation of rolled graphene accompanied by the presence of vertical multi-wall carbon nanotubes (MWCNTs) positioned over stacked graphene sheets. This detailed characterization provides insights into the structural features and arrangement of the synthesized materials, paving the way for a deeper understanding of their potential applications. The pyrolysis temperature is a crucial factor in the morphological characteristics of the synthesized carbon nanostructures. While graphene cage-like structures were obtained at 800 °C, small carbon nanotubes were grafted to larger ones and formed three-dimensional hierarchical morphologies when the annealing temperature increased to 900 °C. The growth mechanism of the carbon nanotubes was explained based on the jet self-extrusion of the generated gases through the inherent pores of the corn seeds. The current technique employed in manufacturing MWCNTs shows significant promise as a green synthesis method for producing catalyst-free MWCNTs suitable for industrial applications including sensors and energy storage materials.
本工作报道了一种简便的方法，在不使用任何外部催化剂的情况下，在石墨纳米片上合成多壁碳纳米管（MWCNTs）。简单来说，黄色玉米种子在氢气气氛中于1050℃热退火3小时，无需任何预处理。值得注意的是，观察到MWCNTs的生长优先发生在玉米壳的外表面。这种简单的方法不仅强调了利用农业副产品合成碳纳米材料的可行性，还突出了这些合成材料在各个领域的潜在应用。通过使用各种技术进行全面分析来检查样品，包括扫描电子显微镜（SEM）、拉曼光谱、傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）和高分辨率透射电子显微镜（HRTEM）。研究结果揭示了卷曲石墨烯的形成，同时存在位于堆叠石墨烯片上的垂直多壁碳纳米管（MWCNTs）。这种详细的表征提供了对合成材料的结构特征和排列的见解，为更深入理解其潜在应用铺平了道路。热解温度是合成碳纳米结构形态特征的关键因素。在800℃时获得了石墨烯笼状结构，当退火温度升至900℃时，小碳纳米管嫁接到较大的碳纳米管上并形成三维分级形态。基于生成的气体通过玉米种子固有孔隙的喷射自挤出解释了碳纳米管的生长机制。目前用于制造MWCNTs的技术作为一种绿色合成方法，对于生产适用于包括传感器和储能材料在内的工业应用的无催化剂MWCNTs显示出巨大的前景。
