Flexible and Highly Efficient Bilayer Photothermal Paper for Water Desalination and Purification: Self-Floating, Rapid Water Transport, and Localized Heat

In view of the sustainable and environmentally friendly characteristics of solar energy, solar water evaporation has been identified as a promising approach to mitigate the global water crises. However, it is still a great challenge to develop a portable, flexible, scalable, and high-performance solar water evaporation material. Herein, a bilayer-structured solar water evaporation material consisting of a top multiwalled carbon nanotube (MWCNT) layer and a bottom polyphenylene sulfide/fibrillated cellulose (PPS/FC) paper was fabricated via a simple vacuum filtration technology for efficient solar water evaporation. The MWCNT layer performs as a light absorber with a high solar absorptance (∼93%) in the wavelength range from 400 to 1200 nm and good light-to-heat conversion capability, while the bottom layer (porous network-structured PPS/FC paper) exhibits excellent water transporting ability, high temperature stability, and good thermal insulating capability (0.0467 W m-1 K-1). Benefiting from the above advantages, an attractive water evaporation rate of 1.34 kg m-2 h-1 was achieved with near ∼95% efficiency under 1 sun irradiation (1 kW m-2). Moreover, the MWCNTs@PPS/FC paper maintains high solar evaporation efficiency after several cycles, indicating long-term durability and good reusability. Moreover, the collected clean water using the MWCNTs@PPS/FC paper from seawater of different salinities, simulated wastewater samples with different pH values or containing heavy metal ions, as well as industrial dyes, satisfy the dri...