Programmable Water/Light Dual‐Responsive Hollow Hydrogel Fiber Actuator for Efficient Desalination with Anti‐Salt Accumulation

Abstract An intelligent fiber actuator that can sense, adapt, and interact with environmental stimuli is highly desirable for numerous applications. However, conventional fiber sensors have difficulty in responding to complex environments with fast sensing and actuation. Herein, water/light dual‐responsive double‐twisted RGO@HHF (hollow hydrogel fiber loaded with reduced graphene oxide) actuators are successfully developed based on dynamic self‐contraction/elongation via twisting, folding, plying, and re‐plying process. Under stimuli by water and light, the twisted RGO@HHF provides a forward and reverse torsional stroke of 3168 and 60° cm⁻¹, respectively. The excellent swelling properties endow the fiber with highly effective water‐responsive ability, and the hollow structure can reduce the water required for fiber to swell. Meanwhile, the RGO loading further accelerates water evaporation and enhances the light response rate of the fiber. After twisting and re‐plying, the double‐twisted RGO@HHF exhibits highly increased elongation and contraction under light/water stimulation. On this basis, a new strategy is proposed for efficient desalination and anti‐salt accumulation. The double‐twisted RGO@HHF can elongate to absorb water and contract to evaporate seawater under sunlight/water stimulation, respectively. The accumulated salt can be dissolved in the seawater during the dynamic process. This study provides a promising approach for realizing sustainable seawater desalination.