The escalating demand for electromagnetic protection against increasingly severe electromagnetic pollution is making the development of advanced electromagnetic wave absorbing material systems imperative. MXene-based electromagnetic wave absorbing fillers demonstrate advantages of lightweight and high efficiency. However, their microscale dimensions hinder the formation of interconnected networks within matrices, resulting in limited electromagnetic (EM) loss mechanisms and narrow effective absorption bandwidths. Herein, we employ wet spinning combined with molten salt-assisted in-situ synthesis to fabricate MAX@rGO (rGMAX_n) fibrous absorbers featuring a hierarchical structure of “columnar cactus covered with MAX spheres”. Precise regulation of MAX phase content enables controlled tuning of the electromagnetic properties of rGMAX_n fibers. Moreover, subsequent in-situ etching further enhances their EM performance, yielding MXene@rGO (rGMX_n) fibers with a hierarchical structure of “columnar cactus decorated with MXene nanosheet clusters”. Freeze-drying is utilized to modulate fiber filling content, and fibrous felts with conductive networks are obtained, which exhibit excellent electromagnetic wave absorption performance. Among them, the as-prepared rGMX₁₀ fibrous felt exhibits good electromagnetic wave absorption performance at a low filling content (10 wt.%) with the RL_max of 54.4 dB and an effective absorption bandwidth of 5.31 GHz. This enhancement originates from improved impedance matching characteristics through fiber-interconnected networks and multiple electromagnetic loss mechanisms enabled by the hierarchical structure. The strategy of in-situ growing hierarchical MXene@rGO fibers establishes a novel approach for developing MXene-based fibrous absorbing materials.

Soft actuators endowed with self-sensing capability become highly sought after in recent years. Ti₃C₂T_x MXene is expected to be used in the development of self-sensing actuators due to its outstanding physical and chemical properties. However, achieving precise deformation feedback of MXene-based actuators remains a challenge, as the resistance change of MXene is not only affected by deformation, but also by temperature, and the decoupling is difficult. Here, a composite ink with temperature self-compensation (0.00125 %·°C⁻¹ of temperature coefficient of resistance) is fabricated by combining MXene and graphite with opposite temperature coefficients of resistance. The composite ink can be written on a variety of substrates, including glass, cellulose paper, and various polymers. Based on this, an ink-cellulose/polymer composite actuator with self-sensing function is actualized. The actuator can achieve accurate real-time deformation feedback by monitoring the resistance signal of ink-cellulose layer, which shows a high linear sensitivity (gauge factor ~ 14.5, coefficient of determination (R²) > 0.99), thereby realizing the perception of touch behavior and distinguishing objects with different weights, softness, and roughness. Besides, a series of biomimetic devices and soft robots with programmable movements (rolling and self-sustained oscillating) are also demonstrated. The results offer new insights for the development of the self-sensing actuators.