Optimization of electromagnetic parameters and efficient wave-absorbing performance of FeSiAl@bimetallic MOF composite wave-absorbing materials constructed by an <i>in situ</i> growth method

FeSi-based materials have recently emerged as promising candidates for electromagnetic wave absorption applications owing to their remarkable electrical conductivity and superior soft magnetic properties. Nevertheless, the simultaneous precise regulation of their electromagnetic parameters and optimization of impedance matching remain a significant challenge. Accordingly, the integration of metal-organic frameworks (MOFs), characterized by their high porosity, large specific surface area, and tunable chemical architectures, has been recognized as an optimal strategy to address this challenge. In this work, we fabricated FeSiAl@ZIF-8/ZIF-67 composites <i>via</i> a two-step <i>in situ</i> growth method on FeSiAl substrates, capitalizing on the intrinsic properties of MOF materials. Comprehensive evaluation of microwave absorption performance with varying MOF loading ratios demonstrated that the composites containing 20 wt% ZIF-8 and 20 wt% ZIF-67 achieved exceptional performance, exhibiting a minimum reflection loss of -58.8 dB with an effective absorption bandwidth of 3.995 GHz. The outstanding microwave absorption performance can be primarily attributed to three key factors: (1) the bimetallic MOF composite effectively optimizes electromagnetic parameters, (2) its porous structure enhances interfacial and dipole polarization while improving impedance matching characteristics, and (3) the promoted multiple reflections and scattering of electromagnetic waves contribute to efficient energy dissipation. This work successfully fabricates FeSiAl@ZIF-8/ZIF-67 composites with enhanced microwave absorption performance and improved impedance matching, providing new insights for the application of FeSi-based magnetic materials in electromagnetic absorption.