Construction of binary assembled MOF-derived nanocages with dual-band microwave absorbing properties

It is challenging to prepare a binary assembled metal-organic framework (MOF) by anisotropic epitaxial growth method. Besides, nanocages (NCs) with hollow structures are often constructed to improve microwave absorbing abilities. Herein, we combine the selective epitaxial growth and hollow engineering technologies to fabricate hybrid MOF-derived NCs. Benefiting from the unique nanocage/porous structure, complementary magnetic/dielectric components and suitable impedance matching characteristics, the optimized absorber (CoNi/TiO₂@PC-NCs) exhibits unique microwave absorbing properties. It is worth noting that the minimum reflection loss (RL_min) of the absorber reaches -65.3 dB, and the overall effective absorption bandwidth (EAB, RL < -10 dB) covers 15.1 GHz (2.9–18 GHz). The maximum EAB under a single thickness covers 4.4 GHz, displaying skipping dual-band coverages at both high and low frequencies. This work might provide a novel perspective for the synthesis of assembled MOF-derived absorbers.