Rhombic dodecahedron Ce-Co/C composites with porous hollow structure for efficient electromagnetic wave absorption

The excellent electromagnetic wave (EMW) absorption performance of metal organic frameworks (MOFs) has attracted a lot of attention. In this work, zeolitic imidazolate framework-67 (ZIF-67) was synthesized hydrothermally using 2-methylimidazole (2-mIm) as the organic ligand, cobalt nitrate hexahydrate (Co(NO3)(2).6H(2)O) as the cobalt source and methanol (MeOH) as the organic solvent. The ZIF-67 was etched with cerium nitrate hexahydrate (Ce(NO3)(3).6H(2)O), leading to rhombic dodecahedron Ce-Co/C composites with porous hollow structure after thermal annealing. In addition, the effect of the content of Ce(NO3)(3).6H(2)O on EMW absorption performance of the Ce-Co/C composites was studied. Specifically, the sample Ce-Co/C-2 (Ce(NO3)(3).6H(2)O): (ZIF-67 = 1:2) showed optimal EMW performance. For the Ce-Co/C-2 based composite with a filling ratio of 45 wt%, a RLmin reached -64.67 dB at 11.12 GHz with a thickness of 2.21 mm. The promising EMW absorption performance of the porous hollow structure was attributed to its large specific surface area and massive defects, multiple reflection/scattering, improved impedance matching and increased dielectric loss. This work provides a reference improve EMW absorption performance of MOF materials through regulating their microstructures. (C) 2022 Published by Elsevier B.V.

Automated summary

In this study, Ce-Co/C composites with a porous hollow structure were synthesized hydrothermally and exhibited excellent electromagnetic wave absorption performance. The content of Ce(NO3)(3).6H(2)O was found to have an impact on the absorption performance of the composites, with Ce-Co/C-2 composite showing optimal performance.