Abstract: The development of water purification device using solar energy has received tremendous attention. Despite extensive progress, traditional photothermal conversion usually has a high cost and high environmental impact. To overcome this problem, we develop a low cost, durable and environmentally friendly solar evaporator. This bi-layered evaporator is constructed with a thermal insulating polyvinylidene fluoride (PVDF) membrane as a bottom supporting layer and plasmonic silver nanoparticles decorated micro-sized hybrid flower (Ag/MF) as a top light-to-heat conversion layer. Compared with the sample with a flat silver film, the two-tier Ag/MF has a plasmonic enrichment property and high efficiency in converting the solar light to heat as each flower can generate a microscale hotspot by enriching the absorbed solar light. On the other hand, the PVDF membrane on the bottom with porous structure not only improves the mechanical stability of the entire structure, but also maintains a stable water supply from the bulk water to the evaporation interface by capillarity and minimizes the thermal conduction. The combination of excellent water evaporation ability, simple operation, and low cost of the production process imparts this type of plasmonic enhanced solar-driven interfacial water evaporator with promising prospects for potable water purification for point-of-use applications.

Key words: bionic, plasmonic, water evaporation, synergistic effect, Ag NPs, hybrid flower