electromagnetic wave

absorption performance

interference shielding

thickness mm

db ghz

impedance matching

microwave absorbing

electromagnetic interference

reflection loss

Chemical Engineering Journal

Metal–organic frameworks (MOF) derivative used as microwave absorber has been attracting extensive interest due to the diversity of host-guest coordination and unique structure at micro/nano-meters level. However, the accurate adjustment of metal-semiconductor interfaces construct remains a great challenge. Here, a novel hierarchical multi-interfacial Ni@C@ZnO microsphere with special Schottky contact structure was successfully fabricated after annealed the bimetallic Ni-Zn-MOF precursor. The unique yolk-shell microsphere was assembled together by the core-shell Ni@C micro-units and ZnO flakes. The uniformly dispersed ZnO flakes were anchored inside the hierarchical conductive carbon matrix. The yolk-shell Ni@C@ZnO materials displayed high-performance microwave absorption after the micro-nano structure and interfacial design were optimized. In particular, with a low mass additive amount of only 25%, the maximum reflection loss (RL) reached −55.8 dB at 2.5 mm, and the effective absorption bandwidth (RL ≤ −10 dB) covered as wide as 4.1 GHz. The excellent microwave absorption performance could be attributed to the polarized interfaces of Ni-C-ZnO, which contributes a metallic/semiconductor barrier. Thus, both magnetic-dielectric synergetic effect and interfacial polarization might lead to an evident absorption. This novel lightweight magnetic MOF-derived composites promise great potential in the practical microwave absorption fields.

MOF-derived yolk-shell Ni@C@ZnO Schottky contact structure for enhanced microwave absorption