Bioinspired Coiled Composite Hydrogel Evaporator with Carbonized Hair for Efficient Solar Desalination and Salt Rejection

Interfacial solar-driven seawater desalination has attracted significant attention. However, achieving both high evaporation rates and excellent salt resistance through advanced structural design and material optimization remains a considerable challenge. Inspired by coiled structures, this study presents a coil-structured solar evaporator (C-SPCH) fabricated by coiling a composite hydrogel containing carbonized hair, sodium alginate, and PVA (poly(vinyl alcohol)). Its coiled architecture enables fast capillary channels and interconnected pores for enhanced water transport and salt tolerance. The irregular surface structure notably increases light-harvesting efficiency, while embedded hydrophilic groups smartly control water molecule states, cutting evaporation enthalpy. Therefore, the C-SPCH evaporator exhibits exceptional performance, achieving an evaporation rate of up to 5.36 kg·m–2·h–1 and an outstanding solar-vapor conversion efficiency of 150% (accounting for the additional environmental energy harvested by the three-dimensional coiled structure). It sustains efficient evaporation across a wide salinity range (0–25 wt %) and operates stably for 10 days in 15 wt % brine without significant performance degradation. This study offers insights into the structural design of solar-driven water evaporation systems, highlighting its significant potential for applications in both seawater desalination and high-salinity wastewater treatment.