Facile Hydrothermal Synthesis of Fe3O4/C Core–Shell Nanorings for Efficient Low-Frequency Microwave Absorption

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• 作者：Tong Wu ; Yun Liu ; Xiang Zeng ; Tingting Cui ; Yanting Zhao ; Yana Li ; Guoxiu Tong
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：March 23, 2016
• 年：2016
• 卷：8
• 期：11
• 页码：7370-7380
• 全文大小：841K
• ISSN：1944-8252

文摘

Using elliptical iron glycolate nanosheets as precursors, elliptical Fe₃O₄/C core–shell nanorings (NRs) [25 ± 10 nm in wall thickness, 150 ± 40 nm in length, and 1.6 ± 0.3 in long/short axis ratio] are synthesized via a one-pot hydrothermal route. The surface-poly(vinylpyrrolidone) (PVP)-protected-glucose reduction/carbonization/Ostwald ripening mechanism is responsible for Fe₃O₄/C NR formation. Increasing the glucose/precursor molar ratio can enhance carbon contents, causing a linear decrease in saturation magnetization (M_s) and coercivity (H_c). The Fe₃O₄/C NRs reveal enhanced low-frequency microwave absorption because of improvements to their permittivity and impedance matching. A maximum R_L value of −55.68 dB at 3.44 GHz is achieved by Fe₃O₄/C NRs with 11.95 wt % C content at a volume fraction of 17 vol %. Reflection loss (R_L) values (≤−20 dB) are observed at 2.11–10.99 and 16.5–17.26 GHz. Our research provides insights into the microwave absorption mechanism of elliptical Fe₃O₄/C core–shell NRs. Findings indicate that ring-like and core–shell nanostructures are promising structures for devising new and effective microwave absorbers.