Rational micro/nano-architecture design of Fe3O4@TiO2/PI/rGO aerogels for integrated broadband microwave absorption, flame retardancy, and moisture resistance

Developing advanced electromagnetic wave absorbing (EMA) materials with strong absorption, thin thickness, broad bandwidth, and low filler loading to address the increasingly severe issue of electromagnetic pollution remains a significant challenge. Herein, leveraging a multi-component strategy, Fe₃O₄@TiO₂/PI/rGO (FTPRG) composite aerogels with a three-dimensional directional porous structure were fabricated through directional freezing and thermal treatment processes. The introduction of magnetic Fe₃O₄@TiO₂ microspheres into the PI/rGO framework not only optimizes the impedance matching characteristics of the material but also generates abundant polarization and magnetic loss mechanisms, thereby enhancing electromagnetic wave absorption. Notably, FTPRG-1 composite aerogel exhibits exceptional electromagnetic wave absorption performance, achieving a minimum reflection loss (RL_min) of −63.2 dB and a maximum effective absorption bandwidth (EAB_max) of 7.44 GHz (10.56–18 GHz) at a low filler loading of 5 wt%. Additionally, FTPRG-1 aerogel exhibits multifunctional integration of moderate hydrophobicity, interesting oil-water separation capacity, flame retardancy and thermal insulation with low thermal conductivity of 30.6 mW m⁻¹ K⁻¹, demonstrating promising potential as an advanced EMA material for complex application scenarios.