Abstract

A two-step method has been adopted to synthesize cobalt nanoclusters in carbon (CoC)-decorated reduced graphene oxide (rGO) from graphene oxide (GO) and ZIF-67 as an excellent stable electromagnetic wave (EMW) absorber. Firstly, the electrostatic force between GO and Co²⁺ gave rise to in situ growth of ZIF-67 on GO (ZIF-67–GO). Then CoC–rGO was obtained by calcination of ZIF-67–GO hybrids. The ligand is introduced as the nitrogen source to GO. The crystal structure, chemical composition, and magnetic properties of CoC–rGO were investigated by x-ray powder diffraction analysis, Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and vibrating-sample magnetometry. The morphology was observed by scanning electron microscopy and transmission electron microscopy. By adjusting the ratio of GO to ZIF-67, the electromagnetic parameters of CoC–rGO can be optimized. It was found that the sample consisting of 10 wt.% CoC–rGO-2 in a paraffin matrix exhibited excellent EMW absorption performance, reaching a minimum reflection loss (RL_min) of −44.77 dB with thickness of 2.1 mm and an effective bandwidth (RL ≤ −10 dB) of up to 5.2 GHz at thickness of 1.8 mm. The results of this study open an effective and simple avenue for the design of EMW absorbers using metal–organic framework (MOF) and low-cost carbon materials.

中文翻译：

---

磁性十二面体CoC装饰的还原氧化石墨烯是优异的电磁波吸收剂

摘要

已采用两步法从氧化石墨烯（GO）和ZIF-67中合成了碳（CoC）装饰的还原氧化石墨烯（rGO）中的钴纳米簇，这是一种出色的稳定电磁波（EMW）吸收剂。首先，GO和Co之间的静电力²⁺引起了原位GO上ZIF-67的生长（ZIF-67-GO）。然后通过煅烧ZIF-67-GO杂种获得CoC-rGO。将配体作为氮源引入GO。通过X射线粉末衍射分析，傅立叶变换红外（FT-IR）光谱，拉曼光谱，X射线光电子能谱和振动样品磁力分析法研究了CoC–rGO的晶体结构，化学成分和磁性能。通过扫描电子显微镜和透射电子显微镜观察形态。通过调节GO与ZIF-67的比例，可以优化CoC–rGO的电磁参数。发现在石蜡基质中由10 wt。％CoC–rGO-2组成的样品表现出出色的EMW吸收性能，达到了最小的反射损耗（RL _min）为-44.77 dB，厚度为2.1 mm，在1.8 mm的厚度下有效带宽（RL≤-10 dB）高达5.2 GHz。这项研究的结果为使用金属有机框架（MOF）和低成本碳材料设计EMW吸收器开辟了一条有效而简单的途径。