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Page 8 of 16 Xu et al. Soft Sci. 2025, 5, 43 https://dx.doi.org/10.20517/ss.2025.63

pillars provide the aerogel with good compressive strength when subjected to external pressure and
strengthen the stability of the lamellar structure, preventing collapse [Figure 3E]. A porous structure
composed of strut-like links was observed [Figure 3F], which increased the propagation paths of the
electromagnetic waves. The synergistic effect of the two materials improves the electromagnetic wave
absorbing efficiency of the material and confers lightweight and high strength.

In the TEM image of the Ti CT /Si N aerogel [Figure 3G], a lattice spacing of 0.45 nm can be observed.
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From the elemental distribution characteristics of the Ti CT /Si N aerogel surface, which correspond to the
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high-angle annular dark-field (HAADF) image [Figure 3H], it can be concluded that the main elements are
Si, N, Ti, C, O, and F [Figure 3I-N, Supplementary Figure 4 and Supplementary Table 2]. The Ti and C
elemental signals can still be detected following the introduction of Si N , suggesting that the original Ti CT
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was not destroyed by the addition of Si N . The weak signals of Ti and C elements are due to the masking of
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the elemental signals by the Si N layer. The elements O and F are derived from the surface functional
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groups of Ti in Ti CT : O from the -OH group and F from the LiF used in the etching process. Based on the
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above analyses, it is shown that Si N is successfully deposited by the CVI process on the surface of Ti CT ,
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which is uniformly distributed and tightly wrapped around the Ti CT nanosheets.
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The successful preparation of the Ti CT /Si N aerogel was further demonstrated by X-ray diffraction
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(XRD) [Figure 4A], at 7.07° and 39.6°, corresponding to Ti CT (002) and (103) crystal planes, respectively.
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A comparison of the two XRD curves reveals that, following the introduction of Si N , a wide, flat scattering
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peak appears at 27.5°. The presence of the ‘bun peak’ confirms the successful introduction of amorphous Si 3
N through CVI. The XPS spectra indicate the presence of Si, N, C, Ti, O elements [Figure 4B]. There are
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two peaks in the Si 2p curve, at 100.1 eV and 101.01 eV, attributed to Si-O and Si-N bonds, respectively
[Figure 4C]. There are two peaks in the N 1s curve, at 398.4 eV and 400.61 eV, which correspond to N-Si
and N-C bonds, respectively, and are mainly in the form of N-Si bonds [Figure 4D]. We can see four peaks
clearly in the C 1s curve, 284.85 eV corresponds to C-C, 286.75 eV corresponds to C-O-C, 288.54 eV
corresponds to C=C and 290.06 eV corresponds to C-C=O [Figure 4E]. There are four peaks in the Ti 2p
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curve, 453.72 eV corresponds to Ti 2p , 457.02 eV corresponds to Ti 2p , 459.8 eV corresponds to
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Ti 2p , and 462.2 eV corresponds to Ti 2p [Figure 4F]. These results indicate the successful preparation
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of the Ti CT /Si N aerogel.
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Dielectric properties and microwave absorption performance
The properties of electromagnetic wave-absorbing materials are described using electromagnetic
parameters, including complex permittivity (ε = ε’ - jε’’) and complex permeability (μ ’ = μ’ - jμ’’) [59,60] . The
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real and imaginary parts of the dielectric constant reflect the stored and lost energy of the electromagnetic
wave, respectively. We tested and compared the electromagnetic parameters of two structures: a biomimetic
layered structure [Figure 5A(1)] and a porous structure [Figure 5B(1)] at 8.2-12.4 GHz. The dielectric
constant (ε = ε’ - jε’’) was measured to demonstrate dielectric properties within the frequency range of 8.2-
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12.4 GHz [Figure 5A(2)]. The ε’ and ε’’ of Ti CT /Si N aerogel with layered biomimetic structure exhibited
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a similar trend at 8.2-10.2 GHz. In this frequency range, ε’ decreases from 2.6 to 2.3, while ε’’ decreases from
2.2 to 1.8. In the 9.6-10.2 GHz frequency range, ε’ increases slightly, and ε shows an overall decreasing trend
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with increasing frequency, which is related to the frequency dispersion effect and caused by polarization
relaxation. When the electric field frequency is too high, the dipole cannot align with the electric field for a
short period. This leads to weak polarization relaxation and consequently a decrease in the dielectric
constant. The μ’ and μ’’ of Ti CT /Si N aerogel are 0 and 1, respectively [Supplementary Figure 5],
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indicating that the aerogel is non-magnetic. Generally, excellent electromagnetic wave absorption
performance depends primarily on the dielectric and magnetic losses of the material. For non-magnetic Ti 2
CT /Si N aerogels, electromagnetic wave absorption mainly depends on dielectric loss. The ε’ and ε’’ of
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