Sequential solar evaporation and selective lithium extraction enabled by hierarchically porous aerogels with high evaporation rate

Solar interface evaporation-assisted resource recovery is among the promising technical solution to the water-energy-resource crisis. However, typically low lithium concentrations in the source solution, e.g., seawater, as well as the dynamic nature of SIE limit the performance of adsorbents. In this study, a “temporal separation” strategy is proposed: the aerogel first concentrates Li+ by solar-driven evaporation and then captures it through selective adsorption. To achieve this, molybdenum disulfide and lithium ion sieves are encapsulated within acrylamide, forming a hierarchically porous aerogel. This structure enhances solar evaporation for rapid Li+ concentration, followed by efficient selective adsorption. Under 1-sun irradiation, the aerogel achieves an evaporation rate of 2.58 kg m−2 h−1 with 90.4 % photothermal efficiency in saline solution, maintaining excellent stability over extended operation. Within 72 h, the Li+ concentration increases fourfold, and the embedded sieves deliver a lithium adsorption capacity of 53.4 mg g−1, with excellent performance retained after 12 cycles. Environmental impact assessment indicates shows lower carbon emissions, energy use, and water footprint than other solar evaporators.