Synergistically regulated surface structure and water transportation of sponge hydrogel evaporator for efficient water desalination

Interfacial evaporation using sustainable renewable solar energy offers an exciting opportunity for desalination and wastewater treatment, while the undesirable evaporation rate and the demanding preparation process severely limit its practical application. In this work, high-efficiency solar steam generators based on sponge like hydrogels were fabricated through a facile and scalable one-step salt template method. In this way, the surface structure of the hydrogel and the water transport rate can be synergistically regulated to enhance the absorption of light and inhibit salt crystallization. Thus, the rationally architected sponge hydrogel evaporators (SHEs) presented a high-water evaporation rate of 2.04 kg m⁻² h⁻¹ with a high energy conversion efficiency of 93.5% under one sun illumination. Meanwhile, the hydrogel evaporator exhibited stable desalination and contaminant removal performance over a long evaporation period. These results suggest that SHEs will offer the opportunity for actual large-scale applications for efficient desalination and wastewater purification.