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Page 16 of 28 Wang et al. Soft Sci. 2026, 6, 8

an exceptional RL of -71.13 dB at 13.76 GHz with a thickness of only 2.46 mm, along with a broad EAB of
7.04 GHz. Wu et al. constructed rich heterogeneous interfaces within a hierarchical structure through a
synergistic strategy combining NaCl templates and freeze-drying, preparing carbon-based EM wave
absorbers loaded with Co/Co(OH) 2 [131] . By controlling the carbonization temperature, remarkable EM
heterostructures and strong interfacial polarization effects were obtained. At a thickness of 2.2 mm, the
optimal RL and EAB reached -25.8 dB and 7.1 GHz, respectively.

The pore size distribution plays a critical role in determining the impedance matching behaviors and the
dielectric loss of carbon-based aerogels [132] . For example, Zhang et al. successfully fabricated RGO-wrapped
cellulose nanofibril (CNF)/GO aerogels with a tunable pore structure [133] . By increasing polyvinyl alcohol
(PVA) concentration from 0 to 15 mg·mL , the average pore size of the RGO@CNF/GO composite aerogels
-1
decreased from 154 to 45 μm, while the dielectric loss tangent increased correspondingly, leading to the
enhancement of the microwave loss capacity. Moreover, the ε′′ values varied with pore size; the
RGO@CNF/GO-15 sample exhibited the highest conduction loss, which is attributed to the optimized pore
size distribution and PVA content, promoting suitable permittivity with interconnected conductive
networks, thereby exhibiting excellent microwave attenuation performance. Besides, Wang et al. reported
uniform vesicle-structured carbon spheres, which show remarkable microwave absorption performance due
to the existence of gradient pore size distributions . First, the large pores with through-hole microstructure
[39]
in the vesicle carbon spheres allow the penetration of the microwave into the interior of the aerogel by
improving the impedance matching behavior. Second, the abundant mesopores with a pore size of 8 nm
promoted the Debye relaxation effect due to the high specific surface area, which enhanced the interfacial
polarization significantly.

Macropores with larger diameters can significantly reduce both the density of the conductive network and
the effective permittivity of the aerogel, which is essential for achieving favorable impedance matching with
free space, thereby minimizing surface reflection and facilitating deeper microwave penetration into the
aerogel [134] . Furthermore, macropores promote multiple internal reflections and scattering by extending the
propagation path of incident microwaves, enhancing energy absorption and dissipation. In addition,
dielectric loss can be tailored by controlling polarization behaviors arising from mesoporous and
microporous structures at the nanoscale. The high specific surface area of the mesoporous structure creates
numerous heterogeneous interfaces between the conductive carbon skeleton and air voids, where charge
carriers can accumulate to form micro-capacitor-like structures, facilitating relaxation behaviors and
enhancing interfacial polarization. Moreover, defects in the micropore walls can act as dipolar centers that
modulate local electron density without significantly altering electrical conductivity and conduction loss,
generating dipole polarization under an alternating EM field and resulting in EM energy attenuation. The
comparison of microwave absorption performance of carbon-based aerogels prepared via the soft-template
method is shown in Table 2.

Non-template strategies
Although the previously mentioned methods for preparing carbon-based aerogels have been widely adopted,
they also exhibit certain shortcomings that make them difficult to meet practical requirements in some cases.
Therefore, non-template strategies with broad applicability have gradually emerged.

For example, electrospinning has attracted widespread attention in constructing MA aerogel [135,136] . Wu et al.
prepared lightweight MXene/C aerogels via electrospinning. The combination of a 3D interconnected
conductive network and heterogeneous components effectively enhanced interfacial polarization and
impedance matching, endowing the aerogel with excellent microwave-absorbing properties: the minimum
RL reached -53.02 dB at a thickness of 3.8 mm [137] . Additionally, the composite aerogel exhibited good