Controllable synthesis of Ni/NiO@porous carbon hybrid composites towards remarkable electromagnetic wave absorption and wide absorption bandwidth

Abstract The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic (EM) wave absorption performance. Herein, the Ni/NiO@C hybrid composites with tunable Ni proportion were successfully synthesized through a two-step process. With the assistance of X-ray diffraction with refinement treatment, the specific proportion of Ni of as-obtained hybrid composites could be obtained. Employing controlling calcination time to adjust the Ni content of Ni/NiO@C hybrid composites, it has been found that the composite carbonized at 500 °C exhibited remarkable EM wave absorption with the minimum reflection loss (RLmin) of -49.1 dB at 4.9 mm and the widest effective absorption bandwidth (EABmax) of 4.56 GHz at 2.1 mm. Moreover, by adjusting the Ni source, the optimal EM wave absorption performance could be achieved. Results illustrated that the N3PC with the Ni proportion of 13.17% showed the RLmin as low as -51.1 dB at 2.4 mm and the EABmax was 5.12 GHz at 2.7 mm. It is worth noting that this work demonstrates the relevance of the composition and EM wave absorption performance of hybrid composites, which offers a feasible reference for the absorption mechanism of absorber.