Anisotropic electromagnetic absorption of the aligned Ti₃C₂T_x MXene/RGO nanocomposite foam

Transition metal carbides/nitrides (MXenes) with superb electrical properties have excellent applications for electromagnetic wave absorption (EMA). Whereas, the three-dimensional (3D) MXene's fabrication assemblies with anisotropic EMA performance are still a challenge as MXene nanosheets have weak gelation capabilities. In this study, graphene oxide was introduced to assist in fabricating the 3D MXene/RGO porous foam through the method of unidirectional freeze casting followed by hydrazine hydrate chemical reduction. Combined with the excellent electrical properties of MXene and RGO, the resultant lightweight (∼6 mg/cm³) MXene/RGO composite foam (MGF) with a free-standing configuration exhibits anisotropic microwave absorption performance. At the sample thickness of 5 mm, MGF-1/2 shows −26.79 dB minimum reflection loss at 4.39 GHz along the perpendicular direction that relates to the unidirectional freeze casting direction. While along the parallel direction, materials with 3 mm thickness reach the maximum effective bandwidth of 8.34 GHz. The lightweight MXene/RGO nanocomposite foam with anisotropic performance may significantly extend the feasibility of MXenes in EMA.