Light‐Fueled Hydrogel Actuators with Controlled Deformation and Photocatalytic Activity

Abstract Hydrogel actuators have shown great promise in underwater robotic applications as they can generate controllable shape transformations upon stimulation due to their ability to absorb and release water reversibly. Herein, a photoresponsive anisotropic hydrogel actuator is developed from poly(N‐isopropylacrylamide) (PNIPAM) and gold‐decorated carbon nitride (Au/g‐C 3 N 4 ) nanoparticles. Carbon nitride nanoparticles endow hydrogel actuators with photocatalytic properties, while their reorientation and mobility driven by the electrical field provide anisotropic properties to the surrounding network. A variety of light‐fueled soft robotic functionalities including controllable and programmable shape‐change, gripping, and locomotion is elicited. A responsive flower‐like photocatalytic reactor is also fabricated, for water splitting, which maximizes its energy‐harvesting efficiency, that is, hydrogen generation rate of 1061.82 µmol g −1 h −1 , and the apparent quantum yield of 8.55% at 400 nm, by facing its light‐receiving area adaptively towards the light. The synergy between photoactive and photocatalytic properties of this hydrogel portrays a new perspective for the design of underwater robotic and photocatalytic devices.