A cryogel solar vapor generator with rapid water replenishment and high intermediate water content for seawater desalination

Abstract

A hydrogel-based solar vapor generator (SVG) system, without any additional energy input, is a promising alternative to current energy intensive desalination technologies. Thermal and water management govern the performance of SVG systems. However, considerable efforts have been devoted to improving thermal management to achieve high evaporation rates, while the research on the water management of hydrogels is still in its early stages, hindering the development of advanced SVGs. Through systematic selection of polymer precursors with appropriate glass transition temperature (T_g), here we developed a novel cryogel SVG system with desired properties for water management, such as interconnected pores, rapid-water-replenishment, a high intermediate water ratio etc. As a result, the resultant cryogels exhibit a high intermediate water content of 67%, a low equivalent evaporation enthalpy of 861.5 J g⁻¹, an excellent evaporation rate of 3.59 kg m⁻¹ h⁻¹ under one sun, high salt resistance and long-term durability in desalination, showing great potential for practical applications.