Facile design of mesoporous spherical cerium oxide@reduced graphene oxide nanocomposites with excellent microwave absorption

Abstract

Mesoporous spherical cerium oxide@reduced graphene oxide (CeO₂@RGO) and mesoporous spherical cerium oxide@multi-walled carbon nanotube (CeO₂@MWCNT) nanocomposites were synthesized through facile hydrothermal and annealing processes, respectively. The CeO₂@RGO nanocomposites (60 mg, 30 wt%), with a thickness of merely 1.39 mm, show an effective absorption bandwidth (EAB) of 6.46 GHz and a minimum reflection loss (RL_min) of −55.03 dB at 13.03 GHz (1.39 mm). Furthermore, the CeO₂@MWCNT (100 mg, 30 wt%) nanocomposites show an EAB of 6.51 GHz at 1.77 mm and a RL_min surpassing −35.00 dB at 4.66 mm. The as-prepared nanocomposites were significantly better than those of previous reports. CeO₂@RGO and CeO₂@MWCNTs effectively enhance the electromagnetic parameters to improve the impedance match. Meanwhile, the three-dimensional conductive structure formed by the mesoporous spherical CeO₂@RGO and CeO₂@MWCNTs provided many reflection paths and improved the interfacial polarization and conduction loss. Furthermore, a high oxygen vacancy concentration of CeO₂ in nanocomposites can promote charge polarization relaxation and lead to conductive loss.