Light-adaptive interfacial solar steam evaporation enhanced by dynamic water gating

Freshwater scarcity is a critical global issue, exacerbated by water pollution. Solar-driven interfacial evaporation (SDIE) offers a promising solution due to its energy efficiency and environmental benefits. This study presents a light-driven adaptive interfacial solar steam evaporation system enhanced by dynamic water gating. The system addresses the challenge of balancing high evaporation rates with salt accumulation, a common limitation in SDIE technology. An evaporator is developed using modified spiropyran and inexpensive wood, enabling dynamic salt discharge through light variations. Theoretical calculations reveal that the reversible structural changes in spiropyrans facilitate salt removal. The evaporator features a two-layer design, with a light-control layer and a hydrophilic layer, which enhances evaporation by stabilizing the gas-liquid interface and minimizing heat loss. Experimental results confirm the evaporator's long-term stable salt-discharge and freshwater production capabilities, demonstrating high evaporation rates, reusability, and pollution resistance. Outdoor experiments and water purification tests further validate its effectiveness in producing freshwater and preventing salt accumulation. This research underscores the potential of light-responsive materials in designing efficient, sustainable evaporators, offering a significant advancement in water purification and desalination technologies.