Structural engineering on carbon materials for microwave absorption: From micro to macro to meta

With increasing problems of electromagnetic interference and pollution, efficient microwave-absorbing materials are urgently needed. Carbon materials have the merits of natural abundance, low density, ease of processing, chemical stability, and excellent attenuation capability, thus are the most promising materials for microwave absorption. Concerning the poor impedance matching and limited microwave dissipation mechanism of simple carbon materials, much work has been devoted to structural engineering on carbon materials to improve their microwave attenuation capability, which is yet to be systematically summarized. Herein, in this review, recent progress on developing advanced carbon materials for enhanced microwave absorption from the perspective of (1) micro structural engineering to tune the dielectric parameters of the carbon materials including morphology tuning, heterogeneous interface engineering and hetero atom doping; (2) macro structural engineering to bring multiple reflections and scattering for dissipation; (3) meta structural engineering to introduce electromagnetic wave resonance dissipation; and (4) multi-layer structural engineering was comprehensively summarized, focusing on rational design, synthesis methods, performance, and mechanisms. Finally, the challenges and future perspectives for structural engineering carbon materials for high performance microwave absorption are proposed.