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Page 12 of 16 Xu et al. Soft Sci. 2025, 5, 43 https://dx.doi.org/10.20517/ss.2025.63

groups on Ti CT , combined with the low dielectric constant of Si N [Supplementary Table 3], work
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synergistically at the Ti CT /Si N interface. The significant disparity in electrical conductivity and dielectric
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constant between the two materials leads to intense charge accumulation and rearrangement under an
[68]
electric field, resulting in the formation of macroscopic electric dipole moments . This loss mechanism
converts electromagnetic wave energy into thermal energy via polarization relaxation, thereby achieving
effective absorption of electromagnetic waves. Additionally, the interfacial polarization between Ti CT and
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Si N significantly enhanced the electromagnetic wave-absorbing properties of the composite; (2) Multiple
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reflections and scattering: the layered porous structure of the Ti CT /Si N aerogel promotes multiple
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reflections and scattering of electromagnetic waves within the material . This structural design
[69]
[70]
significantly increases the propagation path of electromagnetic waves , thereby improving their energy
dissipation efficiency; (3) Impedance matching: The low-dielectric-constant Si N outer layers form a
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graded-index transition zone , which significantly mitigates the abrupt impedance mismatch between air
[71]
and the highly conductive Ti CT layers, thereby markedly reducing surface reflection and increasing the
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depth of electromagnetic wave penetration and absorption efficiency ; (4) Synergistic effect: Ti CT
[72]
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exhibits high electrical conductivity. The conductive network formed by Ti CT nanosheets provides
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pathways for electron migration, generating conduction currents that dissipate electromagnetic wave energy
through a conductive loss mechanism . When Ti CT is compounded with Si N , this mechanism is
[33]
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retained and enhanced by the structural optimization of Si N . The combination of the high electrical
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conductivity of Ti CT and the low dielectric constant of Si N results in an efficient electromagnetic wave
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absorption system [73-75] .
Mechanical properties of Ti CT /Si N aerogel with bidirectional structure
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The freeze-dried Ti CT /Si N aerogel possesses a porous structure that results in a low density. This allows
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it to be easily placed on plant leaves without significantly bending them [Supplementary Figure 11A]. The
combination of the aerogel's anisotropic porous structure and the deposited Si N imparts considerable
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strength to the Ti CT /Si N aerogels. This enables the aerogel to sustain multiple times its own weight
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without fracturing [Supplementary Figure 11B]. When a maximum compressive force of 15.69 kN was
applied, the compressive modulus of elasticity was found to be 14.56 GPa, while the compressive strength
was found to be 315 MPa. This indicates that the Ti CT /Si N aerogel has excellent mechanical properties
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[Supplementary Figure 11B]. Moreover, we investigated the high-temperature stability of Ti CT /Si N
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aerogel further by testing their thermogravimetric curves in air or Ar atmospheres, respectively. In an air
atmosphere, the weight loss begins at 400 °C and plateaus at 1,200 °C, with a loss of only 1.25%
[Supplementary Figure 11C]. In an Ar atmosphere, the weight loss was 1.75% at 1,200 °C [Supplementary
Figure 11D]. The quality of the Ti CT /Si N aerogel remained above 98% in different atmospheres,
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demonstrating its excellent thermal stability.
CONCLUSIONS
In summary, Ti CT aerogel with aligned lamellar porous structure was prepared using a bidirectional
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freeze-drying process. Subsequently, amorphous Si N was infiltrated into the Ti CT using the Chemical
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Vapor Infiltration technique to produce a bionic, porous Ti CT /Si N aerogel with an intercalated lamellar
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structure. The experimental results show that, with a Ti CT concentration of just 0.21 wt.%, the
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Ti CT /Si N composite exhibits an EAB spanning the entire X-band (8.2-12.4 GHz). This is achieved with a
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minimum reflection loss of -53 dB at a thickness of 5 mm. The microwave absorption mechanism of
Ti CT /Si N is attributed to multiple polarizations at the heterojunction interface and multiple reflections
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and conductive losses between Ti CT layers. Meanwhile, the Ti CT /Si N composites prepared show
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advantages in terms of their lightweight properties, robust mechanical properties, and high-temperature
stability, providing important insights for the application of Ti CT in nano-electromagnetic engineering,
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especially in the field of electromagnetic pollution mitigation.