State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, International School of Materials Science and Engineering , Wuhan University of Technology , Wuhan 430070 , China.
College of Chemistry and Life Sciences , Zhejiang Normal University , Jinhua 321004 , China.
ACS Appl Mater Interfaces. 2018 May 16;10(19):16511-16520. doi: 10.1021/acsami.8b02770. Epub 2018 May 1.
This paper demonstrates a facile and low-cost carbothermal reduction preparation of monodisperse FeO/C core-shell nanosheets (NSs) for greatly improved microwave absorption. In this protocol, the redox reaction between sheet-like hematite (α-FeO) precursors and acetone under inert atmosphere and elevated temperature generates FeO/C core-shell NSs with the morphology inheriting from α-FeO. Thus, FeO/C core-shell NSs of different sizes ( a) and FeO/C core-shell nanopolyhedrons are obtained by using different precursors. Benefited from the high crystallinity of the FeO core and the thin carbon layer, the resultant NSs exhibit high specific saturation magnetization larger than 82.51 emu·g. Simultaneously, the coercivity enhances with the increase of a, suggesting a strong shape anisotropy effect. Furthermore, because of the anisotropy structure and the complementary behavior between FeO and C, the as-obtained FeO/C core-shell NSs exhibit strong natural magnetic resonance at a high frequency, enhanced interfacial polarization, and improved impedance matching, ensuring the enhancement of the microwave absorption. The 250 nm NSs-paraffin composites exhibit reflection loss (RL) lower than -20 dB (corresponding to 99% absorption) in a large frequency ( f) range of 2.08-16.40 GHz with a minimum RL of -43.95 dB at f = 3.92 GHz when the thickness is tuned from 7.0 to 1.4 mm, indicating that the FeO/C core-shell NSs are a good candidate to manufacture high-performance microwave absorbers. Moreover, the as-developed carbothermal reduction method could be applied for the fabrication of other composites based on ferrites and carbon.
本文展示了一种简便且低成本的碳热还原法，用于制备单分散 FeO/C 核壳纳米片（NSs），以极大地提高微波吸收性能。在该方案中，在惰性气氛和高温下，片状赤铁矿（α-FeO）前体与丙酮之间的氧化还原反应生成具有α-FeO 形貌特征的 FeO/C 核壳 NSs。因此，通过使用不同的前体可以获得不同尺寸（a）的 FeO/C 核壳 NSs 和 FeO/C 核壳纳米多面体。由于 FeO 核的高结晶度和薄碳层，所得 NSs 表现出高于 82.51 emu·g 的高比饱和磁化强度。同时，矫顽力随 a 的增加而增强，表明存在强形状各向异性效应。此外，由于各向异性结构和 FeO 与 C 之间的互补行为，所获得的 FeO/C 核壳 NSs 在高频下表现出强的自然磁共振、增强的界面极化和改善的阻抗匹配，确保了微波吸收的增强。250nm NSs-石蜡复合材料在 2.08-16.40GHz 的宽频率范围内，当厚度从 7.0 调谐至 1.4mm 时，其反射损耗（RL）低于-20dB（对应 99%的吸收率），最小 RL 可达-43.95dB，在 f=3.92GHz 时，表明 FeO/C 核壳 NSs 是制造高性能微波吸收体的良好候选材料。此外，所开发的碳热还原法可应用于基于铁氧体和碳的其他复合材料的制备。
