NiO nanosheets on pine pollen-derived porous carbon: construction of interface to enhance microwave absorption

Efficient microwave absorbing materials have been drawn extensive attention. Herein, biomass porous carbon (BPC) from pine pollen has been obtained through KOH carbonization. In order to tune the microwave absorption, NiO has been composited with the as-prepared BPC with different contents. Despite the high specific surface area for the BPC activated at 600 °C, it exhibits poor microwave absorption properties as pure NiO. In contrast, the BPC/NiO composite with proper nickel precursor (0.1:1.0) has the maximum reflection loss ( RL ) of − 52.6 dB at 10.0 GHz and the effective absorption bandwidth ( RL  < − 10 dB) reaches up to 4.9 GHz (from 7.8 to 12.7 GHz) when the absorber thickness is 3 mm. Three-dimensional porous architecture, interfacial polarization and their related relaxation from defects and interfaces cooperatively favor the impedance matching and strong EM wave attenuation capacities, which brings about multiple absorption mechanisms of the microwave. The present study not only provides a facile route to prepare porous carbon, but also sheds light on a new strategy in constructing BPC/NiO composites for excellent microwave absorption.