Fabrication of carbon-doped ZnCo2O4 yolk-shell microspheres compounded with magnetic graphene for enhanced electromagnetic wave absorption performance

摘要

Carbon-doped ZnCo2O4 (ZnCo2O4/C) yolk-shell microspheres are synthesized by a method of thermally decomposing precursor and then successfully compounded with magnetic graphene (MG) via co-precipitation in combination with a reduction pathway. The fabrication processes and characterizations (XRD, XPS, TEM, EDS and SEM) are described and explained in detail. It is confirmed that amorphous carbon (in situ decomposition from PVP) is uniformly doped into ZnCo2O4 yolk-shell microspheres. In addition, the reflection loss (RL) and electromagnetic (EM) wave absorption mechanisms of as-prepared ZnCo2O4/C/MG composites are calculated and analyzed exhaustively. The results show that absorption bandwidth with RL exceeding -10 dB reaches up to 4.48 GHz with a matching thickness of 3.5 mm while the maximum RL is up to -52.9 dB at 7.52 GHz with a matching thickness of 3.9 mm. Enhanced EM wave absorption performance can be attributed to good dielectric and magnetic loss, excellent impedance matching, diverse interfacial polarization and multiple reflections caused by special structures.