Poly(dimethylsilylene)diacetylene-Guided ZIF-Based Heterostructures for Full Ku-Band Electromagnetic Wave Absorption

Zeolitic imidazolate frameworks (ZIFs), a group of metal-organic frameworks (MOFs), hold promise as building blocks in electromagnetic (EM) wave absorbing/shielding materials and devices. In this contribution, we proposed a facile strategy to synthesize three-dimensional ZIF-67-based hierarchical heterostructures through coordinated reaction of a preceramic component, poly(dimethylsilylene)diacetylene (PDSDA) with ZIF-67, followed by carbonizing the PDSDA-wrapped ZIF at high temperature. The introduction of PDSDA leads to controllable generation of a surface network containing branched carbon nanotubes and regional distributed graphitic carbons, in addition to the nanostructures with a well-defined size and porous surface made by cobalt nanoparticles. The surface structures can be tailored through variations in pyrolysis temperatures, therefore enabling a simple and robust route to facilitate a suitable structural surface. The heterostructure of the ZIF nanocomplex allows the existence of dielectric loss and magnetic loss, therefore yielding a significant improvement on EM wave absorption with a minimum reflection coefficient (RC_min) of -50.9 dB at 17.0 GHz at a thickness of 1.9 mm and an effective absorption bandwidth (EAB) covering the full Ku-band (12.0-18.0 GHz).