Ternary assembled MOF-derived composite: Anisotropic epitaxial growth and microwave absorption

In recent years, metal-organic framework (MOF)-derived absorbers have attracted much attention in the field of microwave absorption. It is interesting and difficult to construct multiple MOF-on-MOF heterostructures. Herein, we combine two unique anisotropic epitaxial growth strategies to build binary assemblies DUT-52@MIL-88B (DM) and DUT-52@MIL-88C (DMC), and then the ternary assembly DUT-52@MIL-88B@MIL-88C (DMM). The formation mechanisms of the assembled structure are clarified. Besides, they are converted into magnetic porous carbon-based absorbers (DM-700 and DMM-700) through a facile carbonization process. The microwave ab-sorption mechanisms are elucidated. The results indicate that the exquisite multi-element composite structure endows the absorber with suitable impedance matching characteristics, complementary loss mechanisms and excellent electromagnetic loss capabilities. It is worth noting that DM-700 exhibits a remarkable minimum reflection loss (RLmin) of-67.5 dB under a matching thickness of 3.6 mm, corresponding to an effective absorption bandwidth (EAB, RL <-10 dB) of 2.0 GHz and the filler loading of 55%. The optimized absorber DMM-700 successfully achieves the optimization of the above-mentioned microwave absorbing properties. While maintaining the desirable RLmin (-56.4 dB), the matching thickness is reduced (2.4 mm), and at the same time, EAB is doubled (4.0 GHz). This study might provide a new idea for the construction of sophisticated absorbers with multi-MOF-on-MOF structures.

Automated summary

In recent years, metal-organic framework (MOF)-derived absorbers have gained significant attention in the field of microwave absorption. This study successfully constructs binary and ternary assemblies using unique anisotropic epitaxial growth strategies. The resulting absorbers are converted into magnetic porous carbon-based materials with excellent electromagnetic loss capabilities. The optimized absorber achieves improved microwave absorbing properties compared to the initial assembly.