Nanosilver-Coated Organic Porous Films Prepared by the Breath Figure Method for Efficient Solar-Driven Interfacial Evaporation and Hydrogen Production

Solar-driven interfacial evaporation (SDIE) technology has emerged as one of the most sought-after cutting-edge solutions for freshwater production due to its exceptional light-to-heat conversion efficiency. In this study, we developed a novel nanosilver-coated photothermal evaporator (PMMA/AgNPs-EPE) with a bilayer architecture: a solution-processed PMMA/AgNPs photothermal composite film based on the breath figure method (BF) serving as the top layer and polyurethane water-absorbent sponges as the bottom support layer. The engineered PMMA/AgNPs-EPE features a hierarchical porous structure with low-tortuosity vertical channels, demonstrating broadband solar absorption (over 87% in the 250–2500 nm range) and outstanding photothermal conversion efficiency (up to 95% under 1 kW m–2 solar illumination). This configuration enables an evaporation rate of 1.76 kg m–2 h–1 with stable performance retention (>90% of initial efficiency) after 10 operational cycles. Notably, the system maintains a high evaporation rate of 1.65 kg m–2 h–1 even in 15% NaCl brine, highlighting its exceptional salt tolerance. The interception rate for metal ions, such as Ca2+ and Mg2+ in seawater, exceeds 99%, surpassing the drinking water standards set by the World Health Organization (WHO). Furthermore, the PMMA/AgNPs photothermal materials exhibit a potential photocatalytic hydrogen production capability (48.4 mmol m–2 h–1 per cycle), thus presenting a new opportunity to develop novel functional evaporators with enhanced photocatalytic performance. Leveraging the cost-effective, environmentally friendly, and straightforward scaled-up respiratory map preparation method, PMMA/AgNPs holds significant promise as advanced membranes for various high-efficiency SDIE applications in diverse environments.