School of Physics , Northwest University , Xi'an 710069 , China.
Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , China.
ACS Appl Mater Interfaces. 2019 Feb 13;11(6):6374-6383. doi: 10.1021/acsami.8b18875. Epub 2019 Jan 30.
The exploration of high-efficiency microwave absorption materials with lightweight and hydrophobic features is highly expected to reduce or eliminate the electromagnetic pollution. Graphene-based nanocomposites are universally acknowledged as promising candidates for absorbing microwaves due to their remarkable dielectric properties and lightweight characteristic. However, the hydrophilicity of graphene may reduce their stability and restrict the applications in moist environment. Herein, a well-designed heterostructure composed of crystalline permalloy core and amorphous iron oxide shell was uniformly adhered on oleylamine-modified graphene nanosheets by a one-pot thermal decomposition method. Compared with the recognized hydrophilic graphene-based hybrid materials, the permalloy@iron oxide/graphene nanocomposites show excellent hydrophobic and water-resistant features with a water contact angle of 136.5°. Besides, the nanocomposites show high-efficiency microwave absorption performance, benefiting from the tunneling effect, polarization, interface interaction, impedance matching condition, and synergistic effect between core-shell permalloy@iron oxide nanoparticles and graphene nanosheets. A broad effective absorption bandwidth with reflection loss (RL) value exceeding -10 dB can be obtained from 4.25 to 18 GHz, covering about 86% measured frequency range when the absorber thickness is 2.0-5.0 mm. Also, the microwave absorption performance of nanocomposites can be tuned by changing the amount of graphene. More importantly, a greatly improved microwave absorption effectiveness of -71.1 dB can be achieved for the nanocomposites in comparison with the bare permalloy@iron oxide nanoparticles (-5.6 dB) and oleylamine-modified GO nanosheets (-3.56 dB). The lightweight and hydrophobic permalloy@iron oxide/graphene nanocomposites with high-efficiency microwave absorption performance are highly promising to improve the environmental adaptability of electric devices, especially in the wet environment.
具有轻质和疏水特性的高效微波吸收材料的探索备受期待，有望减少或消除电磁污染。由于其显著的介电性能和轻质特性，基于石墨烯的纳米复合材料被普遍认为是吸收微波的有前途的候选材料。然而，石墨烯的亲水性可能会降低其稳定性，并限制其在潮湿环境中的应用。在此，通过一步热分解法，在油胺修饰的石墨烯纳米片上均匀附着了由结晶坡莫合金核和非晶氧化铁壳组成的精心设计的异质结构。与公认的亲水性石墨烯基杂化材料相比，坡莫合金@氧化铁/石墨烯纳米复合材料表现出优异的疏水和耐水特性，水接触角为 136.5°。此外，纳米复合材料表现出高效的微波吸收性能，这得益于隧道效应、极化、界面相互作用、阻抗匹配条件以及核壳结构坡莫合金@氧化铁纳米粒子和石墨烯纳米片之间的协同效应。当吸收体厚度为 2.0-5.0mm 时，在 4.25-18GHz 范围内可获得具有超过-10dB 反射损耗（RL）值的宽有效吸收带宽，覆盖约 86%的测量频率范围。此外，通过改变石墨烯的用量可以调整纳米复合材料的微波吸收性能。更重要的是，与纯坡莫合金@氧化铁纳米粒子（-5.6dB）和油胺修饰的 GO 纳米片（-3.56dB）相比，纳米复合材料的微波吸收效果可提高 71.1dB。具有高效微波吸收性能的轻质疏水坡莫合金@氧化铁/石墨烯纳米复合材料有望提高电子设备的环境适应性，特别是在潮湿环境中。
