Porous carbon sphere decorated with Co/Ni nanoparticles for strong and broadband electromagnetic dissipation

In order to eliminate the hazards induced by electromagnetic pollution, the preparation of microwave absorbing composite incorporating biomass-derived porous carbon with efficient magnetic component has been recognized as a valid route. Herein, a serious of Co/Ni NPs decorated porous carbon sphere were successfully prepared via a combined method of activation, hydrothermal and annealing process. By controlling the addition amount of activator and the concentration of precursor, the appropriate morphology and impedance matching can be obtained in the as-prepared hybrid. Thus, the super-wide EAB of S4 can reach 7.30 GHz for only 2.3 mm thickness, and its maximum RL is −76.54 dB at 12.23 GHz with a thickness of 2.5 mm. This outstanding microwave absorption properties could be attributed to the synergistic effect of magnetic and dielectric loss under decent impedance matching condition, which includes the primary nature and exchange resonance, destructive interference, together with multiple reflection and scattering effect, and the subordinate effect of dipole and interface polarization loss. This work offers a novel route to prepare biomass-derived porous carbon loaded with magnetic NPs for strong and broadband electromagnetic absorption.