A general strategy has been developed here to supramolecular self-assembly of nickel (Ⅱ)-substituted α-Keggin-type polyoxometalate and polyaniline coated Fe₂O₃ hollow nanospindle (Fe₂O₃ hollow nanospindle@PANI/α-SiW₁₁Ni composites) via electrostatic attraction and hydrothermal method. Fe³⁺ was first hydrolyzed and polymerized into Fe₂O₃, then dissolved into [Fe(H₂PO₄)_x]^3−x, resulting in hollow structure. The polyoxometalate existed in polyaniline as a proton-doped counter-ion form, rather than as a separate crystalline state. The protons and anions entered the PANI main chain and combined with N atoms of amines and imines on the PANI chain ((-NH^‧+ ​= ​)/α-[SiW₁₁Ni(H₂O)O₃₉]^6-) to form poles and bipolar delocalization into π bonds of the whole polyaniline molecular chain, which leaded to conductance and polarization. The Fe₂O₃ hollow nanospindle@PANI/α-SiW₁₁Ni composites were proven to be excellent microwave absorber in terms of reflection loss (R_L) and bandwidth. The maximum R_L value was up to −53.6 ​dB at 3.5 ​mm and 6.9 ​GHz. The broadest absorption bandwidth exceeding −10 dB was 6.3 ​GHz at a thickness of only 1.9 ​mm. Moreover, the ternary composites presented obvious multi-band absorption with the matching thickness range of 1.5–5 ​mm. The absorption peaks bandwidth reached as wide as 14.3 ​GHz, which included all C-Ku bands. The hollow and core-shell structures could provide non-uniform interface for the induced polarization loss and space for the reflecting and scattering of microwave. The carrier, pair-ion carrier and hydrogen bond network could lead to conduction loss. The magnetic losses were caused by eddy current effect and natural resonance. This work can lay a theoretical foundation for the design and performance regulation of new absorbing materials.

这里已经开发了一种超分子自组装镍 (II) 取代的 α-Keggin 型多金属氧酸盐和聚苯胺包覆的 Fe ₂ O ₃空心纳米轴（Fe ₂ O ₃空心纳米轴@PANI/α-SiW ₁₁ Ni 复合材料）的一般策略) 通过静电吸引和水热法。Fe ³⁺首先水解聚合成Fe ₂ O ₃，然后溶解成[Fe(H ₂ PO ₄ ) _x ] ^3-x，导致空心结构。多金属氧酸盐以掺杂质子的反离子形式存在于聚苯胺中，而不是作为单独的结晶状态。质子和阴离子进入PANI主链并与PANI链上胺和亚胺的N原子结合((-NH ^‧+ = )/α-[SiW ₁₁ Ni(H ₂ O)O ₃₉ ] ^6- )形成极和双极离域成整个聚苯胺分子链的π键，从而导致电导和极化。Fe ₂ O ₃中空纳米轴@PANI/α-SiW ₁₁ Ni 复合材料被证明是优异的微波吸收剂，在反射损耗方面（R _L) 和带宽。最大 R _L值在 3.5 mm 和 6.9 GHz 时高达 −53.6 dB。超过 -10 dB 的最宽吸收带宽为 6.3 GHz，厚度仅为 1.9 毫米。此外，三元复合材料表现出明显的多波段吸收，匹配厚度范围为 1.5-5 mm。吸收峰带宽达到 14.3 GHz，包括所有 C-Ku 波段。空心和核壳结构可以为诱导极化损耗提供非均匀界面，为微波的反射和散射提供空间。载流子、离子对载流子和氢键网络可能导致传导损失。磁损耗是由涡流效应和自然共振引起的。该工作可为新型吸波材料的设计和性能调控奠定理论基础。