Nanofibrous Hydrogel with Highly Salt-Resistant Radial/Vertical-Combined Structure for Efficient Solar Interfacial Evaporation

Hydrogel-based solar interfacial evaporators, featuring various channels such as random, unidirectional, and radial array, are considered effective for seawater desalination owing to their porous structure, lower evaporation enthalpy, and controllable water transport capacity. However, each individual array structure has its own strengths and limitations, influencing water transportation, thermal management, and salt rejection. By combining the benefits of each array configuration into a single evaporator, the evaporation performance can be maximized. Herein, the study develops a unique nanofibrous hydrogel-based solar evaporator featuring a combined radical/vertical array structure. This integrated structure with external radial and internal vertical channels endows this evaporator with excellent water transport capability and reduced heat loss, resulting in superior evaporation performance and high salty resistance. The addition of nanofibers into hydrogels not only enhances the hydrogel's stability but also facilitates water transport. Under 1 sun illumination, this evaporator can achieve an impressive evaporation rate of 4.62 kg m⁻² h⁻¹ with an energy efficiency of 149.57%. After 12 h of evaporation in a 20 wt.% NaCl solution, it still maintains an average evaporation rate of 3.98 kg m⁻² h⁻¹ with minimal salt accumulation, thereby exhibiting its exceptional salt resistance and durability.