Magnetic-dielectric balance in chain-like CoNi@C heterojunction with enhanced electromagnetic wave absorption

Chain-like magnetic-dielectric composites have become an ideal choice for electromagnetic (EM) wave sorption materials due to their excellent component adjustment and structural optimization. Here, the chain CoNi@C heterojunction was obtained via multi-step reaction combining the solvothermal reaction, polymerization reaction, and annealing treatment. Magnetic chain-like CoNi alloy was firstly synthesized under application magnetic field, where offered the polymerization surfaces for the dopamine monomer. Then, as-prepared CoNi@PDA composites were undergoing the annealing treatment at N2 atmosphere to obtain the chain CoNi@C heterojunction. The EM parameters and impedance match properties of the CoNi@C composites be efficiently regulated via tunning the carbon shell. Combining with the magnetic-dielectric balance and ergy loss absorption, chain-like CoNi@C heterojunction exhibited outstanding EM wave performance. Optimized CoNi@C-7 heterojunction exhibited the minimum reflection loss (RLmin) value can reach to-50.3 dB at 11.92 GHz when the thickness is 1.95 mm and the effective absorption bandwidth (EAB) can up to 4.16 GHz from 13.84 GHz to 18 GHz at only 1.5 mm thickness. Therefore, the chain-like magnetic-dielectric CoNi@C composites provided a new design ideal to fabricate the EM wave absorption materials.