Extremely facile and green synthesis of magnetic carbon composites drawn from natural bulrush for electromagnetic wave absorbing

The green chemistry strives for desired products with sustainable approaches and no using hazardous stuff. Recently magnetic carbon composite absorbers have attracted much attentions for military and civil applications. In this work, an extremely facile and green method of carbonizing metal-precursor impregnated bulrush was proposed to fabricate Co/C and Ni/C nanocomposites for wave-absorbing. The synergistic effect of dielectric loss from carbon biochar and magnetic loss from Co/Ni components, as well as the optimized impedance matching properties and elevated attenuation capabilities, contributed to the excellent absorption performance of Co/C and Ni/C nanocomposites. The minimum reflection loss for Co/C and Ni/C absorbers were −52.42 dB (with thickness of 1.93 mm) and −50.98 dB (with thickness of 2.52 mm), respectively. The widest bandwidth of effective absorbing for Co/C was 4.29 GHz with a thickness only 1.44 mm, and that for Ni/C was 4.47 GHz at 1.57 mm. This work provided a facile way for the mass production of magnetic carbon absorbers through recycling abundant natural plant waste from the point of green chemistry.