Asymmetric Evaporation for Efficient and Simultaneous Extraction of Freshwater, Salt, and Electrical Energy from Seawater

The simultaneous extraction of freshwater, salt, and energy from seawater using solar interfacial evaporation methods still faces significant challenges. Here, a novel asymmetric evaporation model is proposed. This asymmetric evaporation can create differences in water supply/loss ratios at the evaporation surface, thereby elevating salt concentration gradients in specific directions. Consequently, during the freshwater extraction process, solid salt precipitates and accumulates only on the side of the evaporator away from the seawater supply center, facilitating convenient collection. Additionally, the introduction of the positively charged polyacrylamide gel into the evaporator can decelerate the movement of cations in the seawater. This results in a significant potential difference between the evaporator surfaces away from the seawater supply center and those near the seawater supply center, enabling the continuous output of electrical energy. Therefore, the asymmetric evaporation evaporator realizes the efficient simultaneous extraction of freshwater, salt, and electrical energy from seawater.