Ionically conductive NiFe2O4/CNTs organohydrogel composite for boosting efficient electromagnetic wave absorption

Abstract

Gel-based electromagnetic wave (EMW) absorbing materials demonstrate substantial potential in wearable electronics and soft robotics. However, it remains challenging to simultaneously achieve superior impedance matching and efficient electromagnetic energy dissipation through benefiting potential synergies among multifunctional attributes. In this work, a novel salting-out organohydrogel containing 0.5 wt.% NiFe₂O₄/CNTs was successfully synthesized, with a three-dimensional (3D) porous cross-linked structure and multiple heterointerfaces, which dramatically boosts the interfacial effects and improves the polarization loss. Meanwhile, dense polymer networks impose steric hindrance that elevates the energy barrier for molecular reorientation and ionic transport resistance, synergistically amplifying both polarization and ohmic conductive losses. Taking advantage of the features of considerable multiple polarization loss and optimized impedance matching, the as-prepared S-0.5 NiFe₂O₄/CNTs organohydrogel has achieved exceptional EMW absorption performance (the minimum reflection loss RL = −48.31 dB and the maximum adequate absorption bandwidth EAB reaches 6.16 GHz). This as-prepared organohydrogel exhibits optimal radar cross-section (RCS) reduction performance with a maximum value of 21.63 dB m². Such excellent electromagnetic characteristics deepen the mechanistic understanding of internal attenuation processes in gel-based EMW absorbers and provide novel design principles for advancing next-generation flexible electronics.