Reinforced Nacre-Like MXene/Sodium Alginate Composite Films for Bioinspired Actuators Driven by Moisture and Sunlight

MXene-based soft actuators have attracted increasing attention and shown competitive performance in various intelligent devices such as supercapacitors, bionic robots and artificial muscles. However, the development of robust MXene-based actuators with multi-stimuli responsiveness remains challenging. In this study, a nacre-like structure soft actuator based on MXene and sodium alginate (SA) composite films is prepared using a straightforward solvent casting self-assembly method, which not only enhances the mechanical performance (tensile strength of 72 MPa) but also diversifies the stimuli responsiveness of the material. The composite actuators can be powered by external stimuli from renewable energy sources, from moisture inducing a maximum bending angle of 190 degrees at a relative humidity (RH) of 91%, and sunlight irradiation generating a maximum curvature of 1.45 cm^-1 under 100 mW cm^-2. The feasibility of practical applications, including moisture-responsive flowers and walkers, sunlight-responsive oscillators, and smart switches, is demonstrated through comprehensive experimental characterization and performance evaluation. The work presented here provides insight into the design of robust actuators via the utilization and conversion of environmentally renewable energy sources.