Electrically responsive electrochemical actuators that contain a polymer electrolyte membrane laminated between two electrodes have attracted great attention due to their potential applications in smart electronics, wearable devices, and soft robotics. However, some challenges such as the achievement of large bending strain under low applied voltage and fast ion diffusion and accumulation still exist to be resolved. The key to the solution lies in the choice of electrode materials and the design of electrode structures. In this study, an engineering electrochemical actuator that presents large bending strain under low applied voltage based on MXene/polystyrene-MXene hybrid electrodes is developed. The developed electrochemical actuator based on the MXene/polystyrene-MXene 3D-structure is found to exhibit large bending strain (ca. 1.18%), broad frequency bandwidth, good durability (90% retention after 10,000 cycles) and considerable Young’s modulus (ca. 246 MPa). The high-performance actuation mainly stems from the excellent properties of MXene and 3D-structure of the electrode. The MXene provides excellent mechanical strength and high electrical conductivity which facilitate strong interaction and rapid electron transfer in electrodes. The 3D architectures formed by polystyrene microspheres generate unimpeded ion pathways for ionic short diffusion and fast injection. This study reveals that the 3D-structure hybrid electrodes play a crucial role in promoting the performance of such electrochemical actuators.

Novel thin and flexible broadband electromagnetic microwave absorbers are realized with nanocomposites and achieve a wide frequency tunability (from 10 to 17.2 GHz) by actively adjusting the resistance. The proposed absorbers are fabricated by scalable screen printing of optimized nanoparticle ink onto the flexible dielectric composite substrates. Based on the shape memory effects of the substrate and piezoresistive effect of the nanocomposite frequency selective surface, a controllable sheet resistance, and thereby tunable wave absorption performance, can be realized in a temperature-activated and dynamically stable manner. The results provide new dimensions for the design of active electromagnetic devices by utilizing previously underestimated intrinsic properties of the artificial materials and the smart behavior of polymer-based nanocomposites.