Controllable structures porous carbon cages for high-efficient lightweight electromagnetic wave absorption

Previous studies have demonstrated that the porous carbon cages can regulate electromagnetic parameters and optimize impedance matching. However, the controllable preparation of porous carbon cages with pore size and shell thickness remains a significant challenge. In this study, porous carbon cages were fabricated via a polymerization-hydrolysis-pyrolysis method and achieved gram-scale production. The results show that the pore size (6.40 nm, 5.75 nm, 4.83 nm, and 3.89 nm) and shell thickness (80 nm, 110 nm, 150 nm and 190 nm) of the porous carbon cages can be controlled by changing the content of the coating monomer. Finally, the porous carbon cage with a relatively high specific surface area (662.8 m²·g− 1), a pore diameter of 4.83 nm and shell thickness of 150 nm exhibits an impressive effective absorption bandwidth (EAB) of 4.76 GHz, along with a remarkable minimum reflection loss (RLmin) of -56.03 dB at 12.88 GHz and a simulated radar cross-section reduction value of 28.58 dBm2. These results were achieved with a thin matching thickness of 2.5 mm and a low filler loading of 9.09 wt%. This method establishes a foundation for the controllable preparation of porous carbon cages. Controllable synthesis of porous carbon cages enables a systematic study on pore-size-dependent conductive loss and impedance matching. An optimal pore size of 4.83 nm delivers superior EMW absorption (RLmin: -56.03 dB, EAB: 4.76 GHz) by balancing conductive loss and impedance matching. Remarkable RCS reduction of 28.58 dBm²is achieved with an ultralow filler loading of 9.09 wt%, highlighting the material's lightweight characteristic and practical potential.