Pagoda solar evaporators with an alternating hot-cold pattern for rapid, scaling-free desalination of hypersaline brines

Solar-driven evaporation holds significant potential for desalinating hypersaline brines, which pose challenges for traditional reverse osmosis. However, achieving both rapid evaporation and scaling prevention remains a key obstacle. In this study, we introduce a pagoda-like solar evaporator designed to optimize heat and mass transfer during the evaporation process of hypersaline brines. The interconnected multi-layer structure creates an alternating hot–cold pattern that integrates solar and environmental evaporation, enhancing the overall evaporation rate. This pattern also induces thermal Marangoni convection within the evaporator, mitigating local ion accumulation and providing durable scaling resistance. The pagoda evaporator sustains an evaporation rate of approximately 1.70 kg·m −2 ·h −1 over 8 h with a 20 wt% NaCl solution and produces 7.78 L·m −2 ·day −1 of fresh water without surface scaling in outdoor experiments. This innovative and facile design marks a significant advancement in the sustainable and efficient desalination of highly saline brines.