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Page 4 of 16 Xu et al. Soft Sci. 2025, 5, 43 https://dx.doi.org/10.20517/ss.2025.63

METHODS
Materials
Ti AlC powders were purchased from Lianlixin Technology Co., Ltd., China. Lithium fluoride (LiF) and
2
hydrochloric acid (HCl) solution were obtained from Aladdin Reagent. Silicon tetrachloride (SiCl ≥
4
99.99%), ammonia (NH ≥ 99.99%), Hydrogen (H ≥ 99.99 %), and argon (Ar ≥ 99.9%) were obtained from
3
2
Xian Wei Guang Gas Co., Ltd. All compounds were utilized immediately without additional purification
unless otherwise indicated.

Preparation of few-layered Ti CT nanosheets
X
2
Few-layered Ti CT nanosheets were synthesized by selectively removing aluminum atoms from Ti AlC
2
2
X
powders using an etching solution. The etchant was formulated by dissolving 1.0 g of LiF in 30 mL of 10 M
HCl, resulting in a homogeneous acidic solution for subsequent etching reactions. The preparation
procedure commenced with the gradual addition of Ti AlC powder into the etchant solution under constant
2
magnetic stirring. The resultant mixture was subjected to continuous agitation at ambient temperature for
72 h to facilitate complete etching. Subsequently, the etched powder underwent multiple centrifugation
cycles (5 min per cycle at 6,000 rpm) using deionized (DI) water until a neutral pH of 6.5 was attained. The
purified sediment was vacuum-dried for 72 h, and the final dried powder was kept until further use.
Preparation of porous Ti CT /Si N composites
4
X
2
3
The porous Ti CT aerogel with an aligned lamellar structure was prepared via a bidirectional freezing
2
X
method. The homemade Teflon tubes (23 mm × 11 mm × 30 mm) were sealed with a copper plate and a
polydimethylsiloxane (PDMS) wedge titled to an angle of 20°. Ti CT slurry with a concentration of 10
X
2
mg/mL was poured into the mold and then frozen in liquid nitrogen. The frozen samples were put in a
vacuum freeze dryer to move the ice template for 36 h under 0.1 Pa pressure. Then the porous Ti CT /Si N 4
X
3
2
composite was fabricated by infiltrating Si N into the obtained Ti CT foams at 1,073 K in a chemical vapor
X
3
4
2
infiltration furnace with a gaseous atmosphere of SiCl -NH -H -Ar system, the deposition parameters of
4
3
2
SiCl -NH -H -Ar system in Supplementary Table 1. The specific constituents comprised silicon
3
2
4
tetrachloride as the silicon source, ammonia as the nitrogen source, and hydrogen as the dilution gas.
Ti CT /Si N composites were obtained after the entire chemical vapor infiltration procedure was
X
2
3
4
completed. The chemical reaction is as follows :
[57]
Simulation calculation
The model has a thickness of 5 mm in the Z-axis using the Microwaves & RF/Optical module in CST Studio
Suite 2020, with the material set to MXene from the material library. Periodic boundary conditions are set
in the XY-axis. A perfectly matched layer is set in the Z-axis direction and a perfectly conductive layer is set
in the Z-axis. The incident electromagnetic wave is directed along the Z axis, and calculations are performed
at 8.2, 10.3, and 12.4 GHz to determine current density, E, power flow, and power loss density.
Characterization
The X-ray diffractometer (X’Pert Pro, Philips, Netherlands) confirmed the microstructure of samples, while
morphology was characterized on a scanning electron microscope (SEM, HITACHI S-4700, Japan) and a
transmission electron microscope (TEM, G20, FEI Tecnai, USA). The thermal stability of Ti CT and
2
X
Ti CT /Si N was measured in ambient air and argon respectively by a thermogravimetric analyzer (TGA,
X
2
4
3
STA449F3, Netzsch) from 30 to 1,200 °C.