Multi-Scale Design of Metal–Organic Framework Metamaterials for Broad-Band Microwave Absorption

The development of nanocomposite microwave absorbers is a critical strategy for tackling electromagnetic pollution. However, challenges persist regarding material stability and achieving broadband absorption. Herein, a novel multi−scale design approach for metamaterial absorbers is proposed. First, a series of bimetallic (cobalt and copper) semiconductive metal–organic framework (SC−MOF) crystals with atomically resolved structures are successfully prepared to serve as building blocks for metamaterials. By simply adjusting the concentration ratio of the two ions, the controllable preparation of crystal morphology can be achieved. This enables to precisely tune the absorption peak and bandwidth range of the SC−MOF, resulting in excellent EMW absorption performance (effective absorption bandwidth: 6.16 GHz, minimum reflection loss: −61 dB). Based on this, printable inks are further constructed by encapsulating the SC−MOF in polydimethylsiloxane and 3D-printed multi−layered metamaterial absorbers based on woodpile porous architecture. The metamaterial absorber demonstrates a near-perfect absorption in the microwave spectrum (with a bandwidth of 11.33 GHz), closely matching theoretical simulations. This multi−scale design approach, combining precise MOF materials construction with topological structure design, offers new insights for the development of broadband microwave absorbers.