Structuring dense three-dimensional sheet-like skeleton networks in biomass-derived carbon aerogels for efficient electromagnetic interference shielding

Developing ultralight, highly conductive carbon aerogels with facilely tunable microscopic structure is still a long-standing issue to effectively shield the electromagnetic interference (EMI). Here, highly porous and conductive all biomass-derived carbon aerogels were first successfully achieved by carbonizing cellulose aerogels, which held excellent structure designability by controlling cellulose content in lithium hydroxide/urea aqueous solution, porogen composition in solvent exchange process, as well as freezing rate during freeze-drying. The as-prepared cellulose-derived carbon aerogels with optimized structure of small pore size and dense three-dimensional sheet-like skeleton network were demonstrated to be highly efficient to greatly prolong the propagation path of electromagnetic waves (EMWs) and dissipate incident EMWs into heat energy, exhibiting the dominant EMI shielding mechanism of EMW absorption. As a result, an impressive EMI shielding effectiveness of as high as 93.1 dB in the X band frequency range at a density of as low as 0.079 g cm−3 was achieved. Of more practical significance is that the new insight into the relationship between microscopic pore structure of carbon aerogels and their EMI shielding performance provides a valuable clue in developing highly efficient EMI shielding carbon aerogels in the application of microelectronics, aircraft and spacecraft.