Facile synthesis and electromagnetic wave absorption properties of silver coated porous carbon composite materials

Biomass porous carbon (PC) has become a novel microwave absorbing material because of its ultralow density, high dielectric loss capability and friendly to environment. In this study, we prepare Ag/PC composite materials by a simple hydrothermal method from 120 °C to 160 °C. By changing the reaction temperature, the electromagnetic parameters are adjusted and the absorption performance is optimized. XRD results prove the successful preparation of Ag/PC composite materials at various temperatures. SEM and TEM images show the Ag particles are attached on the outer surface and inner wall of PC. The compositing of Ag particles promotes the graphitization of porous carbon and forming a conductive network, which help to improve the complex permittivity. The Ag/PC composite material synthesized at 160 °C exhibits the optimal absorbing performance. The reflection loss value below −10 dB reaches in the frequency range of 10.4–12.4 GHz for the sample in 1.8 mm thickness, with a minimum value of −35.4 dB at 11.56 GHz. The results demonstrate that incorporating with Ag is an efficient way to improve the absorbing performance of PC. This work helps to develop high performance biomass porous carbon based microwave absorption materials.