Environmentally Friendly Bark-Derived Co-Doped Porous Carbon Composites for Microwave Absorption

Biomass-derived porous carbon has attracted tremendous attention in many research fields due to its cheap and feasible strategy. In this work, bark-derived porous carbon composites (Co@PC) for microwave absorption applications was successfully prepared through a simple method. The minimum reflection loss (RLmin) of Co@PC (carbonized at 800°C, Co2+ concentration is 0.15 mol/L) is -49.2 dB at 10 GHz and a wide effective absorption bandwidth (EAB) of 6.16 GHz was obtained. Further, by adjusting carbonization temperature of the bark, the microwave absorption performance could be further enhanced. The results show that the RLmin could be -58.4 dB at 8.6 GHz when the bark was carbonized at 900°C. The retained channel structures of the bark played an important role in this excellent microwave absorbing performance. The channel walls with Co nanoparticles form a three-dimensional conductive network, endow conductive loss and magnetic loss of microwave energies. The channel structures provide transmission path for microwaves, which is not only cause multiple reflections and scattering of microwaves, but also benefit to the impedance matching. In addition, radar cross section (RCS) simulation results also demonstrates that Co@PC can be applied in the field of microwave absorption.