Multi-stimulus responsive actuator with weldable and robust MXene-CNTs hybrid films

Abstract

Stimulus-responsive actuators are novel functional devices capable of sensing external stimuli and exhibiting specific deformation responses. MXene, owing to its unique 2D structure and efficient energy conversion efficiency, has bridged the gap in traditional devices and shown great potential for multiple stimulus-responsive actuators. However, the drawbacks of pure MXene films, including susceptibility to oxidation and vulnerability to shear stress, hinder their applications. Through composite modification and structural design strategies, a three-layer structured MXene-carbon nanotubes hybrid film (tHCM) is fabricated, exhibiting a tensile strength and fracture strain of 153.8 MPa and 4.65%, respectively, representing improvements of 598.4% and 226.8% compared to the initial film. Meanwhile, the film maintains excellent stability demonstrating the enhancing effects of hydrogen bonds and densely packed structure. The hybrid films demonstrate unique and facile welding features due to splicing properties, enabling the formation of complex configurations. In terms of electro-/photo-thermal conversion performance, the hybrid film can reach a reasonably high temperature of 250 ℃ at low voltage (2.5 V) and 110.6 ℃ under 150 mW cm^–2 infrared light. Leveraging the thermal expansion mismatch between tHCM and thermoplastic films, an integrated, flexible, and weldable actuator with unique electro/photo-response is developed, and various biomimetic driving applications, particularly, the light-mediated hierarchical transmission and precise motion along predetermined trajectory are realized. This work not only provides an effective strategy for modifying MXene composite films but also advances the design of novel actuators, offering broad application prospects in fields such as stimulus-responsive actuated robots and cargo transportation.