The Rise of Hydrogel‐Based Moist‐Induced Electric Generators: Comprehensive Review and Future Directions

Moisture‐induced electricity generation as an emerging technology can harvest clean and renewable energy from ubiquitous atmospheric moisture, offering promising solutions to alleviate the global energy crisis. Among the various functional materials explored, hydrogels have emerged as highly promising candidate for constructing high‐performance hydrogel‐based moist‐induced electric generators (HMEGs), due to their superior water absorption, outstanding mechanical flexibility, and adjustable physicochemical properties. However, a comprehensive understanding of the underlying material design principles, performance optimization strategies, and practical applications remains lacking. In this review, the fundamental working mechanisms and relevant development of HMEGs are first briefed, followed by current system classifications based on composition and structural characteristics. Next, efficient strategies to improve energy conversion efficiency and output power of HMEGs through rational material engineering, electrode design, and synergistic energy harvesting approaches are summarized. Moreover, representative applications of advanced HMEGs, including self‐powered electronics, sensors, and information displays are presented. Finally, the existing challenges and the perspective of HMEGs are proposed for potential new developments of this emerging technology.