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Wang et al. Soft Sci. 2026, 6, 8 Page 9 of 28

Figure 3. (A) Schematic of the preparation process, (B) microstructure, (C) RL properties, and (D) microwave absorption mechanism of
CNTs-CF [86] . Reproduced with permission [86] . Copyright 2023, ELSEVIER. RL: Reflection loss; CNTs-CF: carbon nanotubes-carbon foam;
MF: melamine foam.

In addition to melamine foam, polyurethane and phenolic resins have also been used as hard templates
[87]
[88]
for constructing carbon-based porous materials decorated with hetero-components via hydrothermal and
thermal treatments. A comparison of the microwave absorption performance of carbon-based aerogels
prepared by hard-template methods is presented in Table 1. In summary, hard-template methods can
successfully produce porous carbon-based MAM with inherent hierarchical structures and tailored
components, enabling convenient regulation of EM response characteristics.

Soft-template methods
Although research on carbon-based aerogels prepared from 3D templates has made significant progress in
microwave absorption, the fixed porous structure and the surface modification limit the wide-range
regulation of the EM response behaviors. Adopting the soft-template method is an effective strategy to
address the above issue.

Freeze-drying strategy
Freeze-drying is the most employed soft-template method. During the freezing process, as ice crystals grow,
the components in the suspension are concentrated and confined in the spaces between them, forming a
solid skeletal structure templated by the ice. Subsequently, under low-temperature and high-vacuum
conditions, the ice crystals sublimate directly into vapor, leaving a porous structure that replicates the spaces
previously occupied by the ice, resulting in an aerogel with high porosity.