Heterostructured magnetic composites with exchange coupling effects are considered to be promising electromagnetic wave (EMW) absorbers. In this work, tailored heterostructures of soft magnetic ZnFe₂O₄ and hard magnetic Fe₃C are generated and tightly anchored on two-dimensional (2D) carbon nanosheets, by in-situ blowing and carbonization process of gel precursor. Nanosized soft/hard magnetic phases generate large number of heterogeneous interfaces. Density functional theory (DFT) calculations confirm the exchange coupling effect that results from the dynamic charges reconstruction of soft/hard magnetic heterogeneous interface. The synthesized Fe₃C/ZnFe₂O₄/C (FZC) shows wide EAB of 4.56 GHz and RL_min value of -65.6 dB. By layer-to-layer stacking of 2D FZC and reduced graphene oxide (rGO), the obtained flexible rGO/FZC-1 film can effectively shield 5G signals. Importantly, both the 2D morphology and abundant heterostructures restrain the diffusion of saline ions inside the FZC coatings and enhance the “maze effect”, finally improving the corrosion resistance in marine environment. This work provides advanced nanostructure integrating 2D morphology and soft/hard magnetic heterostructure with effective exchange coupling, which can simultaneously achieve the EMW stealth and high corrosion resistance.

Using silicon/reduced graphene oxide (Si/rGO) composites as lithium-ion battery (LIB) anodes can effectively buffer the volumetric expansion and shrinkage of Si. Herein, we designed and prepared Si/rGO-b with a sandwiched structure, formed by a duple combination of ammonia-modified silicon (m-Si) nanoparticles (NP) with graphene oxide (GO). In the first composite process of m-Si and GO, a core–shell structure of primal Si/rGO-b (p-Si/rGO-b) was formed. The amino groups on the m-Si surface can not only hybridize with the GO surface to fix the Si particles, but also form covalent chemical bonds with the remaining carboxyl groups of rGO to enhance the stability of the composite. During the electrochemical reaction, the oxygen on the m-Si surface reacts with lithium ions (Li⁺) to form Li₂O, which is a component of the solid–electrolyte interphase (SEI) and is beneficial to buffering the volume expansion of Si. Then, the p-Si/rGO-b recombines with GO again to finally form a sandwiched structure of Si/rGO-b. Covalent chemical bonds are formed between the rGO layers to tightly fix the p-Si/rGO-b, and the conductive network formed by the reintroduced rGO improves the conductivity of the Si/rGO-b composite. When used as an electrode, the Si/rGO-b composite exhibits excellent cycling performance (operated stably for more than 800 cycles at a high-capacity retention rate of 82.4%) and a superior rate capability (300 mA h/g at 5 A/g). After cycling, tiny cracks formed in some areas of the electrode surface, with an expansion rate of only 27.4%. The duple combination of rGO and the unique sandwiched structure presented here demonstrate great effectiveness in improving the electrochemical performance of alloy-type anodes.