Peymanfar Reza, Ghorbanian-Gezaforodi Shaghayegh
Department of Chemical Engineering, Energy Institute of Higher Education, Saveh, Iran.
Nanotechnology. 2021 May 7;32(19):195201. doi: 10.1088/1361-6528/abe0e4.
In this research, a bioinspired carbon structure was applied as a novel, unique, green, affordable, light weight, thin, and broadband microwave absorbing material. Briefly, the monarch butterfly wing scales were pyrolyzed and then CBWs were functionalized using oxidative treatments, following that they were ornamented by hexagonal β-Co(OH) nanoparticles to improve their microwave absorbing features based on an innovative complementary method by combining sonochemistry and hydrothermal routes. Noticeably, the polyacrylonitrile (PAN) was used as a practical medium to fabricate the microwave absorbers developing an integrated structure and augmenting the relaxation loss mechanism. Various analyses were applied to identify the prepared samples including x-ray powder diffraction, diffuse reflection spectroscopy, Fourier transform infrared, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer, and vector network analyzer. The net-like morphology of FCBWs were fully coated by the hierarchical hexagonal β-Co(OH) nanoparticles. FCBW illustrated a saturation magnetization of 0.06 emu g originated from its defects, distortions, dislocations, unique morphology, as well as folding, developing localized magnetic moments. Noticeably, inserting FCBWs narrow the energy bandgap of β-Co(OH) nanoparticles, amplifying their light absorption and polarizability, desirable for the microwave attenuation. As revealed, FCBW/β-Co(OH)/PAN nanocomposite gained strong reflection loss (RL) of 68.41 at 9.08 GHz, while FCBW/PAN achieved broadband efficient bandwidth as wide as 7.97 GHz (RL > 10 dB) with a thickness of 2.00 mm. More significantly, β-Co(OH)/PAN nanocomposites demonstrated salient efficient bandwidth of 3.62 GHz (RL > 20 dB) with only 2.50 mm in thickness. Noteworthy, the eye-catching microwave absorptions were obtained by only filler loading of 10 Wt%. The remarkable microwave absorbing properties of the samples were generated from their microwave absorbing mechanisms which were scrupulously dissected. More significantly, the negative imaginary parts were obtained, originated from the produced secondary fields.
在本研究中，一种受生物启发的碳结构被用作一种新型、独特、绿色、经济、轻质、超薄且宽带的微波吸收材料。简而言之，对帝王蝶翅膀鳞片进行热解，然后通过氧化处理对碳纳米带进行功能化，随后用六方β-Co(OH)纳米颗粒对其进行修饰，以基于声化学和水热路线相结合的创新互补方法改善其微波吸收特性。值得注意的是，聚丙烯腈（PAN）被用作制备微波吸收体的实用介质，以形成一种集成结构并增强弛豫损耗机制。采用了各种分析方法来鉴定制备的样品，包括X射线粉末衍射、漫反射光谱、傅里叶变换红外光谱、场发射扫描电子显微镜（FE-SEM）、透射电子显微镜（TEM）、振动样品磁强计和矢量网络分析仪。分级六方β-Co(OH)纳米颗粒完全包覆了FCBW的网状形态。FCBW由于其缺陷、畸变、位错、独特形态以及折叠而产生局部磁矩，表现出0.06 emu g的饱和磁化强度。值得注意的是，插入FCBW会缩小β-Co(OH)纳米颗粒的能带隙，增强其光吸收和极化率，这对于微波衰减是有利的。结果表明，FCBW/β-Co(OH)/PAN纳米复合材料在9.08 GHz处获得了68.41的强反射损耗（RL），而FCBW/PAN在厚度为2.00 mm时实现了高达7.97 GHz（RL > 10 dB）的宽带有效带宽。更显著的是，β-Co(OH)/PAN纳米复合材料在厚度仅为2.50 mm时表现出3.62 GHz（RL > 20 dB）的显著有效带宽。值得注意的是，仅通过10 Wt%的填料负载就获得了引人注目的微波吸收性能。样品显著的微波吸收性能源于对其微波吸收机制的仔细剖析。更重要的是，获得了负虚部，这源于产生的二次场。
