Water Hydrogen-Bond Disruption in Molecularly Engineered Polyelectrolyte Janus Evaporators for Enhanced Solar Desalination

Recent advancements in solar-driven interfacial evaporation have shown promise in addressing global water scarcity, yet significant challenges remain in enhancing the water evaporation rate and salt rejection. Our recent groundbreaking research has redefined the understanding of polyelectrolyte-water interactions, developing Janus hydrogel evaporator with polyelectrolyte-shell micelle grafted on the surface and revealing biparental groups on the polyelectrolyte effectively disrupted hydrogen bonds in water network. Technically, we developed an electric-field-driven polyelectrolyte grafting strategy to evenly and stably graft a monolayer of polyelectrolyte-shell micelles onto hydrogel, allowing their responsive conformational changes under electric field to entangle with the hydrogel network. This strategy establishes a Janus evaporator with a high-density polyelectrolytes layer on the evaporation surface, effectively lowering the chemical potential and ensuring sufficient water supply. Moreover, by molecular engineering, the biparental polyelectrolyte, the optimized configuration has a synergistic balance between water attraction via electrostatic interactions and water repulsion via steric hindrance. This configuration effectively disrupted the water's hydrogen bond network, lowering the water evaporation enthalpy to 1434 J g-¹, surpassing prior benchmarks. Additionally, the grafted micelle layer exhibited a salt rejection ratio of 99.62%, ensuring excellent desalination performance. The biparental polyelectrolyte-shell micelles grafting strategy is applicable across diverse hydrogel systems, representing a great advancement in solar-driven desalination technology.