Superwetting monolithic hypercrosslinked polymers nanotubes with high salt-resistance for efficient solar steam generation

Solar-driven water evaporation is emerging as a promising strategy to utilize solar energy for the desalination and water purification . In this work, two kinds of monoliths based on hypercrosslinked polymers (HCPs) nanotubes , which were synthesized using inexpensive and conventional chemicals, i.e. benzene and methylbenzene as building blocks via Friedel-Crafts reaction, have been created as photothermal materials through a superhydrophilic modification followed by the coating of polypyrrole as light absorption layer . The as-synthesized HCPs possess large specific surface area (up to 773 m 2 g -1 ) and low apparent density (0.011 g cm -3 ), which endow them very low thermal conductivity (0.029 W m -1 k -1 ). After modification with sodium alginate and polypyrrole, the resulting HCPs (named as PPy-M-HCPs) show surface superhydrophilicity (water contact angle ~0°), stronger light absorption (ca. 95%) and better mechanical properties . Taking advantages of these unique physicochemical properties mentioned above, the PPy-M-HCPs exhibit outstanding light-to-heat conversion performance with a high solar conversion efficiency of ca. 87% achieved under 1 kW m -2 irradiation. In addition, the PPy-M-HCPs also show excellent salt-resistant performance, e.g. a high energy conversion efficiency of more than 85% obtained in 20 wt% NaCl solution, due to their loosely porous structure coupling with their superhydrophilic wettability . Based on the merits of simple fabrication process, excellent stability and high solar conversion efficiency, the PPy-M-HCPs may have great potentials as efficient photothermal materials for real applications.