Advanced Optimizing Strategies for Hydrogels toward Solar-Driven Artificial Freshwater Generation: Current Progress and Future Perspectives

Abstract Global freshwater scarcity is escalating at an alarming rate, driven by inherent shortages, uneven distribution, population growth, and industrialization. Artificial freshwater generation (AFG) through the efficient conversion of nonconventional water resources (NCWR, e.g., seawater, wastewater, and atmospheric water) offers a promising solution. Photoresponsive hydrogels are particularly attractive, harnessing solar irradiation to convert NCWR into freshwater while avoiding the high energy consumption of conventional technologies including reverse osmosis and thermal distillation. However, systematic reviews on the precise customization of hydrogels for solar-driven AFG remain scarce. This review presents recent advances in hydrogels for solar-driven AFG. We first examine the concept, structural features, and design orientations of hydrogels for AFG, followed by a detailed discussion of optimization strategies across seawater desalination, wastewater treatment, and atmospheric water harvesting. Finally, we present a forward-looking perspective on critical challenges, materials innovation, mechanistic insights, technology development, and application expansion, aiming to provide a comprehensive reference for researchers in this field.