Double-layered montmorillonite/MoS2 aerogel with vertical channel for efficient and stable solar interfacial desalination

The shortage of fresh water is becoming a great challenge all over the world, solar desalination is an emerging green and sustainable strategy to produce clean water from seawater or waste water by utilization of renewable solar energy. However, the accumulation of salt will depress the long-term sustainable use of solar evaporators. In this work, a hydrogel evaporator with montmorillonite (Mt) and MoS2 integrated layered structure has been fabricated for stable and efficient solar steam generation. The perfect hydrophilicity of Mt. can facilitate water transmission and salt redissolution speed. The vertical radial porous structure and low thermal conductivity of Mt. hydrogel ensures the shortest water transport path and superior heat localization performance. The upper MoS2 layer has a light absorption rate of up to 92% in the entire solar spectrum (200-2500 nm), which enables an excellent solar to thermal conversion efficiency. Under a low solar irradiation intensity of only 1 kW.m(-2), the Mt./MoS2 double-layer aerogel can achieve a high evaporation rate of 1.31 kg.m(-2).h(-1). More importantly, the Mt./MoS2 double-layer aerogel can produce freshwater with salt ions (Na+, K+, Mg2+, Ca2+) rejection rate over than 99.9%. The as-prepared solar evaporator aerogel is turned out to show good mechanical strength, superior water supply, excellent durability and outstanding desalination performances. As a result, the developed Mt./MoS2 double-layer aerogel with low cost and high-quality of condensed water may provide a good prospect in solar desalination application and wastewater treatment.