Taking the increasing issue of electromagnetic waves (EMW) pollution and the necessity for applications in extreme environments, there is a pressing requirement to create multifunctional microwave absorption materials (MAMs) to meet the current challenges. In this work, we achieved the successful combination of MXene sheets and MOFs derived CoNi@C magnetic alloys onto the three-dimensional (3D) melamine foam (MF) skeleton using vacuum impregnation and electrostatic self-assembly techniques. The obtained MF@MXene/CoNi@C composite foams achieved outstanding MA performance, with an optimal reflection loss (RL) value of -24.1 dB and a maximum effective absorption bandwidth (EAB) of 6.88 GHz at a thickness of 1.68 mm, effectively covering the whole Ku band. The superior MA performance is ascribed to the composite foams' multi-component architecture, distinctive 3D porous structure, and the synergistic impact of multiple loss mechanisms. Moreover, the MF@MXene/CoNi@C composite foams demonstrate exceptional photothermal conversion, thermal insulation, and infrared stealth capabilities, effectively coping with the demands of applications in extreme environments. This work serves as a valuable resource and source of inspiration for the development of lightweight-broadband, multifunctional efficient MAMs.

Aerogel-based composites hold promising application prospects as potential electromagnetic wave (EMW) absorption materials, yet the construction of such materials with ingenious microstructures, appropriate magnetic/dielectric multi-components, and integrated multifunctionality remains considerably challenging. Herein, a multicomponent Co/MnO/Ti₃C₂T_x MXene/rGO (CMMG) hybrid aerogel featured with three-dimensional (3D) vertical directional channel architecture is reported. Benefiting from the synergistic effect arising from the 3D conductive networking structure, diverse heterogeneous interfaces, magnetic/dielectric multicomponent, and multiple loss pathways, the optimized CMMG-2 aerogel delivers fascinating EMW absorption capabilities, characterized by a minimal reflection loss (RL_min) of −77.41 dB and an effective absorption bandwidth (EAB) of 6.56 GHz. Additionally, the remarkable hydrophobicity, exceptional thermal insulation capabilities, and outstanding photothermal properties of CMMG-2 aerogel make it highly promising for multiple application in diverse and demanding environments. Interestingly, the distinctive pore structure of hybrid aerogel also allows it for sensitive and reliable detection of electrical signals caused by pressure changes and human motion. Thus, this research provides a viable design strategy for the development of lightweight, efficient, and multifunctional aerogel-based EMW absorption materials for various application scenarios.

A novel type of three-dimensional ultralight aerogel sphere, consisting of one-dimensional nanocellulose-derived carbon fibers and two-dimensional graphene layers, was prepared based on a developed drop-freeze-drying followed by carbonization approach. The nanofibrous carbon efficiently prevents the agglomeration of the graphene layers, which, in turn, reduces the shrinkage and maintains the structural stability of the hybrid carbon aerogel spheres. Consequently, the aerogel spheres showing an ultralow-density of 2.8 mg/cm³ and a porosity of 99.98% accomplish the tunable dielectric property and electromagnetic wave (EMW) absorption performance. The high-efficiency utilization of biomass-derived fibrous nanocarbon, graphene, and the porous structure of the hybrid aerogel spheres leads to the excellent EMW absorption performance. The aerogel spheres display an effective absorption bandwidth of 6.16 GHz and a minimum reflection loss of −70.44 dB even at a filler loading of merely 3 wt.%, significantly outperforming that of other biomass-derived carbon-based EMW absorbing materials. This work offers a feasible, facile, and scalable approach for fabricating high-performance and sustainable biomass-based aerogels, suggesting a tremendous application potential in EMW absorption and aerospace.

With the rapid development of the electronic industry and wireless communication technology, electromagnetic interference (EMI) or pollution has been increasingly serious. This not only severely endangers the normal operation of electronic equipment but also threatens human health. Therefore, it is urgent to develop high-performance EMI shielding materials. The advent of hydrogel-based materials has given EMI shields a novel option. Hydrogels combined with conductive functional materials have good mechanical flexibility, fatigue durability, and even high stretchability, which are beneficial for a wide range of applications, especially in EMI shielding and some flexible functional devices. Herein, the current progress of hydrogel-based EMI shields was reviewed, in the meanwhile, some novel studies about pore structure design that we believe will help advance the development of hydrogel-based EMI shielding materials were also included. In the outlook, we suggested some promising development directions for the hydrogel-based EMI shields, by which we hope to provide a reference for designing hydrogels with excellent EMI shielding performance and multifunctionalities.