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Page 2 of 16 Xu et al. Soft Sci. 2025, 5, 43 https://dx.doi.org/10.20517/ss.2025.63

realm of electromagnetic pollution mitigation.

Keywords: Ti CT , amorphous Si N , bio-inspired lamellar structure, ice-templated method, microwave absorption
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INTRODUCTION
Over the past 20 years, the integration of nanomaterials with dielectrics and electromagnetic fields has
[1,2]
flourished , achieving remarkable accomplishments across various domains. Among these, nano-
functional materials applied to protect against gigahertz (GHz) electromagnetic wave pollution have
[7]
emerged as a hot topic in research and applications . With the continuous advancement of technology ,
[3-6]
the increasing popularity of electronic devices and their higher operating frequencies and power levels have
[8,9]
led to an increase in the severity of GHz electromagnetic wave pollution . This poses a significant threat to
both human health and the normal functioning of electronic devices [10-14] . Electromagnetic wave absorbing
materials could eliminate electromagnetic pollution based on absorption, and the electromagnetic energy
can be directly converted into non-polluting energy, such as heat , thus avoiding the secondary pollution
[15]
of electromagnetic waves. To meet the diverse needs of practical applications, electromagnetic wave-
absorbing materials must have good mechanical properties and functionality.

Natural materials owe their unique performance not merely to their intrinsic chemistry but to ingenious
structural design that orchestrates interactions among constituents. Today, macro-, micro-, and nano-scale
architectures are engineered to unlock a material’s full potential [16-20] . For example, the human skull consists
[21]
of two layers: a dense layer of bone and a loose porous cancellous bone layer . This layer has a three-
dimensional (3D) porous sandwich structure and good compressive strength [22-24] . This is sufficient to
protect the brain from external loads during daily human activities. The porous structure of plants plays a
[25]
vital role in transporting nutrients , providing mechanical support and regulating the transpiration
process and replicating moth eyes to introduce gradual transitions that prevent abrupt impedance jumps
[26]
and enable broad-band impedance matching . By sculpting intricate 3D geometries - porous networks,
[27]
honeycombs, foams, and labyrinthine channels - electromagnetic waves are forced to undergo multiple
reflections, scattering, and diffraction inside the material, greatly extending their propagation paths and
dissipating their energy [28,29] . The integrative nature of natural materials - simultaneously providing
electromagnetic absorption, mechanical load-bearing, and lightweight characteristics - offers a blueprint for
architecting materials across micro- and macro-scales, opening new avenues for electromagnetic-wave-
absorbing materials.

MXene is a new type of two-dimensional (2D) [30,31] , layered, transition-metal-based material with a unique
physical structure that can be used to produce electromagnetic wave-absorbing composite materials [32-34] .
First, the surface of MXene is abundant in functional groups (e.g., -OH, -O, -F) . These functional groups
[35]
generate dipole polarization in the presence of an electromagnetic field, enhancing the dielectric loss
capability of the material . Furthermore, MXene can self-assemble into 3D porous structures under the
[36]
influence of electrostatic and van der Waals forces . Secondly, MXenes have high electrical
[37]
conductivity , enabling the formation of an effective conductive network and improving the conductive
[38]
loss. Third, its 2D layered structure can effectively enhance the multiple reflections and scattering of
electromagnetic waves within the material , thereby improving its absorption efficiency [40-42] . Therefore,
[39]
assembling 2D MXenes into 3D structures can effectively enhance electromagnetic wave absorption
performance. Zhao et al. blended graphene oxide with an MXene suspension and coated MXene nanosheets
onto the surface of a reduced graphene oxide (rGO) skeleton . This process yielded MXene/rGO hydrogels
[43]
that were freeze-dried to create a 3D porous structure, with shielding effectiveness of more than -50 dB in