Portable solar interfacial evaporator based on polyimide nanofiber aerogel for efficient desalination

Solar vapor generation is a friendly water purification technology via efficiently utilization of natural sunlight. However, the present solar evaporation devices are impeded by high cost, inferior mechanical property, low efficiency and poor durability. Here, inspired by plant transpiration, we designed and fabricated a scalable and portable polypyrrole-modified polyimide nanofiber aerogel (PPy-PI NAG) for efficient and durable solar vapor generation. During the evaporation process, the bottom hydrophilic PI NAG with hierarchical cellular fibrous structure acts as the roots for fast water transportation, while the upper PPy layer with porous and rough surface plays as the leaves for evaporation. More importantly, the highly porous PPy-PI NAG possesses a low thermal conductivity (0.05 W m-1 K-1), which can confine the heat energy on the air-water interface, exhibiting superior heat localization effect. Under one sun illumination, the PPy-PI NAG exhibits a high average evaporation rate of 1.42 kg m- 2 h-1 and achieved 99.7 % ion removal efficiency for seawater. Moreover, the PPy-PI NAG exhibits stable evaporation efficiency with continuous desalination for 15 days and compressing/folding for 1000 cycles, and can be compressed or folded into small size to the benefit of carriage or transportation, demonstrating great potential as portable solar evaporation device for personal and household evaporation systems.