Efficient microwave absorption with ultra-thin thickness through one-step direct calcination of pellicle of Castanea mollissima Blume

Currently, biomass-based absorbers have drawn much attention as microwave absorption materials due to their intrinsic low-weight, low cost, green, and easy availability. However, additional activation methodologies are often employed, significantly elevating cost. In order to overcome this drawback, we use a common biowaste of the inner skin of Chinese chestnut, i.e., the pellicle, often directly discarded in the candied chestnut industry, as the raw material to synthesize a very low-cost biomass-based absorbers (CMs) through one-step facile pyrolysis without further activation or modification. The results show that these materials can exhibit excellent microwave absorption capabilities if the activation temperature is carefully chosen. Calcinated at 700 °C, CM-700 shows strong microwave absorption performance, and the maximum reflection loss is as strong as − 56.73 dB. Moreover, the effective microwave absorption bandwidth of CM-800 reaches 5.09 GHz (ranging from 12.91 to 18.00 Hz) under the ultra-thin thickness of just 1.6 mm. A plausible energy-dissipation mechanism of the pellicle-based materials is proposed.