To improve electromagnetic (EM) wave attenuation and its absorption properties, herein, for the first time, we grow needle-like magnetic NiCo₂O₄ nanoparticles in situ on lightweight open cell reticulated vitreous carbon (RVC) foam by the hydrothermal method, leading to hierarchically nanostructured foam. The foam was synthesized by the carbonization of flexible polyurethane foam followed by acid treatment. The coating structure, stability, and performance were systematically investigated by various complementary techniques using XRD, XPS, Raman, and FTIR spectroscopies, compression test, and ultrasonication. The foam coated for 12 h exhibited considerably improved shielding effectiveness (SE), i.e., ∼36 dB from ∼23 dB for the bare RVC foam in the X-band, leading to ∼99.97% shielding efficiency. Although the foams mainly showed reflection-dominated properties regardless of the coating, the EM absorption improved with coating. The shielding mechanism is explained by means of reflection and absorption coefficients and dielectric and magnetic losses manifested by NiCo₂O₄ coating and interfacial polarization.

中文翻译：

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在轻质网状玻璃碳泡沫上原位涂覆针状 NiCo2O4 磁性纳米颗粒以实现更好的电磁波吸收

为了改善电磁 (EM) 波衰减及其吸收特性，我们首次在此生长针状磁性 NiCo ₂ O ₄通过水热法在轻质开孔网状玻璃碳（RVC）泡沫上原位制备纳米颗粒，从而形成分层纳米结构泡沫。该泡沫是通过软质聚氨酯泡沫碳化和酸处理合成的。通过使用 XRD、XPS、拉曼和 FTIR 光谱、压缩测试和超声波处理的各种互补技术系统地研究了涂层结构、稳定性和性能。涂覆 12 小时的泡沫表现出显着提高的屏蔽效率 (SE)，即从 X 波段裸 RVC 泡沫的~23 dB 提高~36 dB，导致~99.97% 的屏蔽效率。尽管泡沫主要表现出以反射为主的特性，而与涂层无关，但随着涂层的增加，EM 吸收得到了改善。₂ O ₄涂层和界面极化。