Hierarchically Structured Hydrogels for Rapid Solar Vapor Generation With Super Resistance to Salt

Abstract Solar water evaporation is a promising technology for producing clean water from seawater and wastewater. However, the challenge of balancing high evaporation performance and long‐term salt resistance has hindered the widespread application of evaporators. Herein, a dual‐network hydrogel (DNH) featuring a hierarchical structure with alternating pore sizes is introduced. This innovative design optimizes the continuous supply of water to the evaporation surface while improving light absorption. By fine‐tuning the amide groups within the hydrogel network, the state of water, leading to efficient water activation and a significant reduction in evaporation enthalpy is altered. As a result, the DNH achieves an evaporation rate of 4.0 kg m −2 h −1 under one sun. During the solar desalination process, the enhanced convection‐diffusion reflux facilitated by the hierarchical structure endows the DNH with exceptional salt resistance. Remarkably, even after 12 h of continuous evaporation in artificial seawater with 25 wt% salinity, the DNH maintains the same evaporation rate as pure water. This remarkable performance significantly expands its potential applications, positioning the DNH as a transformative solution in the quest for sustainable water resources.