Nitrogen-doped lychee-like saccharide-based carbon microspheres with high-performance microwave absorption

The reasonable design of multiple interfaces and heteroatom doping can substantially improve the waveabsorbing performance of electromagnetic wave (EMW) absorbing materials. As the carbon source of biomass, the carbon material with abundant oxygen-containing groups on the surface can be obtained by hydrothermal method, which is conducive to modification and design of the morphology. In addition, N-hydroxymethyl acrylamide contains rich N atoms and has good water solubility, which can be well combined with sugar to prepare high-performance wave-absorbing materials. In this study, D-xylose and glucose were used as carbon sources, water was used as solvent, N-hydroxymethyl acrylamide was added, and nitrogen-doped lychee-like saccharide-based carbon microspheres (LSCMs) were obtained by hydrothermal synthesis and high-temperature carbonization. LSCMs-2 with good EMW attenuation capability and impedance matching performance was obtained by controlling the proportion of different raw materials. Under the optimal filling conditions, the EMW absorber is only 2 mm thick and achieves a minimum reflection loss (RL min) of -47.44 dB at 13.84 GHz with an effective absorption bandwidth (EAB) of 12.24-17.36 GHz (5.12 GHz). The excellent EMW attenuation performance is mainly attributed to dipole polarization and interface polarization in the LSCMs. This research offers a new green synthesis route for the preparation of EMW absorbers with wider bandwidth, thinner thickness and better absorption performance.