Facile synthesis of ultralight and porous melamine-formaldehyde (MF) resin-derived magnetic graphite-like C3N4/carbon foam with electromagnetic wave absorption behavior

Abstract

Society demands effective electromagnetic wave (EMW) absorbers that are lightweight, with a broad absorption band and strong absorption, to solve excessive electromagnetic radiation. Herein, ultralight magnetic graphite-like C3N4 /carbon foam (MCMF) was fabricated via impregnating polymerized melamine formaldehyde (MF) foams in Fe3O4 nanoparticle solution, followed by in situ pyrolysis at 1000◦C. MCMF possesses porous architectures consisting of graphitic C3N4 /carbon and CFe15.1. The magnetic particles (α-Fe, Fe3O4 and Fe3C) were formed and modified on the internal skeleton surface. The EMW absorption capacity of MCMF is better than the that of carbonized MF foam without Fe3O4 (CMF), possessing excellent absorption behavior, with a minimum RL value of −47.38 dB and a matching thickness as thin as 3.90 mm. The corresponding effective absorbing bandwidth is as broad as 13.32 GHz. Maxwell–Wagner–Sillars (MWS) polarization and the residual loss are proved to be beneficial for such superior absorption behavior. Besides, graphitic C3N4 enriches the interface polarization effect and the electromagnetic matching effect. The microporous structures are beneficial for increasing EMW propagation, resulting in internal multiple reflections and scatterings, which are also beneficial for EMW attenuation.