Photoresponsive Actuators Built from Carbon-Based Soft Materials

Photoresponsive soft actuators with photomechanical energy conversion and flexibility have attracted significant interest in recent years owing to their unique merits of flexibility, contactless operation, and remote control, as well as their multiple technological applications ranging from bionic robotics and biomedical devices to nanomotors. Seeking efficient photoresponsive materials with high energy conversion efficiency and robust mechanical properties and identifying effective photoactuation mechanisms are of paramount significance for the development of advanced photoactuators. Due to their unique optical properties, high mechanical strength, superior electrical and thermal conductivity, good flexibility, and stability, carbon-based materials are regarded as attractive candidates for high-performance photoresponsive actuators. Furthermore, easy functionalization or hybridization with other functional species substantially extends the functions of these materials and widens the application scope for photoactuators. Herein, this review summarizes the recent progress of photoactuators based on various carbon-based soft materials, including 0D, 1D, 2D, and 3D nanocarbons as well as their functional soft composites with other responsive materials. Multiple driving schemes of photoresponsive actuators including photothermal, photomechanical, photoelectronic, and photochemical effects, photoactuating architecture design, and potential technological applications of photoactuators are elucidated. Furthermore, certain future opportunities and challenges in the ever-flourishing optical-to-mechanical energy conversion area are emphasized and discussed.