Scalable liquid-phase synthesis of core–shell absorbers: Synergistic dielectric/magnetic losses dominating microwave attenuation

Dielectric-magnetic composite material that incorporate both dielectric and magnetic loss mechanisms are progressively emerging as the design paradigm for high-performance electromagnetic wave (EMW) absorbing materials. However, it remains challenging to combine dielectric and magnetic materials through a convenient structural design. Here, we report a core–shell structured Fe₃O₄@copper sulfide with multiple loss mechanisms, combining the typical magnetic component Fe₃O₄, which has excellent magnetic loss and impedance matching, with the dielectric component copper sulfide, which has high electrical conductivity and rich interfaces. Unlike the conventional hydrothermal synthesis method, the Fe₃O₄@copper sulfide core–shell structure is formed using the polymer-assisted electrodeless metal deposition (PAMD) method and a subsequent solution based sulfidation reaction. Attributed to the strong dielectric loss capacity introduced by copper sulfide nanosheets, Fe₃O₄@copper sulfide has an effective absorption bandwidth (EAB) of 5 GHz within 2–18 GHz at a filling ratio of 65 wt.% and a thickness of only 1.4 mm. In addition, we used the same possess to synthesize FeSiCr@copper sulfide, which also exhibited EMW absorption performance superior to that of the original magnetic component, verifying that the PAMD method is also applicable to other magnetic particles. Therefore, the proposed PAMD method provides a new solution-based strategy for constructing high-performance EMW absorbing materials with multi-component and multi-loss mechanisms.