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.