Cleaning synthesis of core–shell structured Ni@PPy composite as excellent lightweight electromagnetic wave absorber

A novel electromagnetic functionalized Ni@PPy composite was synthesized with a cleaning method. XRD and FTIR analyses showed that the Ni@PPy composite was successfully prepared. SEM, TEM, and HRTEM results proved that Ni nanoparticles, produced by the γ-irradiation-induced reduction method, were wrapped with polypyrrole (PPy) shell to form core–shell structure. There existed many Ni cores in a PPy shell, which could induce more interfacial and dipolar polarization than the structure with one core in a shell. With an increase in Ni content, the dielectric loss was obviously decreased and the magnetic loss had little change. Attenuation constant decreased gradually, which was influenced jointly by conductivity loss and dipolar and interfacial polarization loss. When nPy/nNi/nAPS was 1.75:1:1.75, the as-prepared Ni@PPy composite exhibited the highest microwave absorption (RL max of − 48 dB at 7 GHz and EAB of 3.8 GHz) owing to suitable impedance matching as well as attenuation ability. Therefore, such core–shell structured Ni@PPy composite would be a promising microwave absorber.