Urea-Assisted Green Synthesis of CeO₂ Nanoparticles/Porous Carbon Composites for Microwave Absorption

The development of economical, high-efficiency synthesis approaches is the primary field of concern for research on microwave-absorbing materials (MAMs). In this work, we used the hydrothermal approach to effectively manufacture CeO 2 nanoparticles/porous carbon composites enriched with oxygen vacancies under urea-assisted conditions. The carbon source for these composites was the porous carbon generated from bamboo powders. We adjusted the electromagnetic characteristics of the composites to optimize their electromagnetic wave (EMW) attenuation mechanisms and impedance matching properties by altering the heat treatment temperatures and the extra quantity of cerium salts. The creation of many defects and heterostructures as a result of the nitrogen/oxygen doping and oxygen vacancy-rich CeO 2 leads to better EMW attenuation, conductivity loss, and increased polarization effects. The remarkable microwave absorption ability of the C2-500 composite is attributed to good impedance matching and interfacial polarization as well as dipole polarization induced by a significant number of heterogeneous interfaces and oxygen vacancies, particularly from N/O heterogeneous elements. At a filler loading of 10 wt %, C2-500 exhibits a minimum reflection loss (RL min ) of −44.94 dB at 16.16 GHz, accompanied by an effective absorption bandwidth (EAB) of 4.72 GHz. In comparison, the C3-500 composites demonstrate an EAB of 4.88 GHz and an RL min of −46.81 dB at 9.28 GHz. This study is expected to be instrumental in the design of high-performance biomass-derived porous carbon-based MAMs, providing valuable insights for future research in this field.