Electromagnetic pollution is a threat to human health and electronic equipment. Therefore, studies on the means of absorbing electromagnetic waves are important. Wave absorbing material with the characteristic of lightweight and high microwave-absorption efficiency is in urgent demand. Biomass hierarchical porous carbon (BHPC) with micropores, mesopores, and macropores derived from rice husk was prepared using potassium hydroxide activation and one-step carbonization. The adjustment and optimization of the pore structure of BHPC can be realized by controlling the heat treatment temperature. When the thickness is 2.8 mm, the BHPC samples obtained at 650 °C show excellent electromagnetic wave absorption properties. The minimum reflection loss (RL_min) is - 47.463 dB at 9.796 GHz, and the effective absorption bandwidth accounts for 81% of the X-band (8.473–11.875 GHz). It shows good absorption performance for electromagnetic waves, due to good impedance matching, high dielectric-loss capacity, large specific surface area, and reasonable pore diameter distribution. This study suggests that the porous carbon from rice husk has a broad prospect as a lightweight and efficient electromagnetic absorbing material.

电磁污染是对人体健康和电子设备的威胁。因此，研究吸收电磁波的方法具有重要意义。急需具有重量轻、吸波效率高的吸波材料。使用氢氧化钾活化和一步碳化制备了源自稻壳的具有微孔、中孔和大孔的生物质分级多孔碳 (BHPC)。BHPC孔结构的调整和优化可以通过控制热处理温度来实现。当厚度为 2.8 mm 时，在 650 °C 下获得的 BHPC 样品表现出优异的电磁波吸收性能。最小反射损耗（RL _min) 在 9.796 GHz 时为 - 47.463 dB，有效吸收带宽占 X 波段 (8.473–11.875 GHz) 的 81%。由于具有良好的阻抗匹配、高介电损耗能力、大比表面积和合理的孔径分布，它对电磁波表现出良好的吸收性能。该研究表明，稻壳多孔碳作为一种轻质高效的电磁吸波材料具有广阔的前景。