▎ 摘　　要

Developing advanced electromagnetic wave (EMW) absorbing materials with high reflection loss, low packing load and thin matching thickness is an effective strategy to solve EMW pollution. In this work, the thin graphenelike multifold carbon nanosheets were synthesized by a facile hydrothermal method and subsequent annealing treatment of watermelon flesh. The unique twisted and folded structure not only improves the conductive loss, but also increases the multiple reflection and scattering through extending the propagation path of EMW. The minimum reflection loss of the watermelon pulp biochar reaches -50.0 dB at a thickness of 3 mm, and the effective absorption bandwidth reaches 3.51 GHz at a thickness of 2 mm. This work provides a new direction and preparation skill to design advanced EMW absorbing materials.