Achieving Enhanced Electromagnetic Shielding and Absorption Capacity of Cellulose-derived Carbon Aerogel via Tuning Carbonization Temperature

High-performance electromagnetic (EM) shielding and absorption materials are in great demand due to the increasing electromagnetic pollution problem in current society. In this study, a lightweight biomass-derived cellulose carbon aerogel (CCA) was prepared via facile carbonization of a cellulose aerogel (CA) under a moderate temperature. Interestingly, the conductivity of CCA could be easily adjusted through changing the carbonization temperature, and higher conductivity was achieved for CCA treated at a higher carbonization temperature due to the differences in the carbon crystal size and carbonization degree of the carbon materials. As a result, the EM shielding performance of CCA is effectively enhanced through increasing the carbonization temperature due to the simultaneously improved dielectric loss and reflection loss, and a superior special shielding effectiveness of 117 dB cm3 g−1 was obtained for CCA700. In addition, based on the good balance between the impedance match and attenuation capacity of CCA640, it displays excellent EM absorption performance, with a minimum reflection loss (RL) of −51.24 dB and a wide effective absorption bandwidth (RL < −10 dB) of 7.68 GHz. Finally, it should be noted that a porous structure is also beneficial for the absorption and dissipation of microwaves through multiple reflections and scattering between adjacent cell walls. In conclusion, the suitable carbonization temperature and special porous structure are the key factors for tuning the EM shielding and absorption capacity of CCA, which will provide an important reference for its practical application in information and military areas.