Hydrogel-Based Solar Interfacial Evaporators: Design, Performance, and Applications

Hydrogel-based solar-driven interfacial evaporators have recently emerged as high-efficiency and sustainable technology for desalination. By leveraging the unique three-dimensional network, remarkable hydrophilicity, and tunable physicochemical properties of hydrogels, these systems achieve efficient solar absorption and thermal conversion, significantly enhancing water evaporation rates. This review summarizes design strategies based on physical and chemical cross-linking, and explores key approaches for performance enhancement, including reduction of evaporation enthalpy and structural optimization. Through regulation of water states and construction of multi-scale porous and biomimetic architectures, synergistic improvements in photothermal conversion, water transport, and thermal management have been realized. Furthermore, hydrogel-based evaporators demonstrate great potential in integrated applications such as wastewater treatment, salt collection, and hydroelectric generation. Finally, challenges related to water purification applications are discussed. This review offers valuable insights for the future design of hydrogel-based solar evaporators to mitigate global water scarcity.