A lotus leaf-inspired Janus dual-functional nanofiber evaporator for efficient water purification

Solar-driven interfacial evaporation is a promising way for clean water production to alleviate freshwater shortage. However, the inability to simultaneously remove organic pollutants (especially volatile organic compounds, VOCs) from condensed and feed water without secondary pollution is always an insurmountable defect. Herein, a lotus leaf-inspired Janus dual-functional evaporator was prepared by subtly modifying polydopamine (PDA) and beta-FeOOH on the surface of electrospinning polyacrylonitrile membrane, which can achieve source water purification and efficient steam generation at the same time. PDA endowed the evaporator a strong photothermal conversion capability, ensuring an excellent evaporation rate of 1.74 kg m-2 h-1 under one sun. Significantly, benefited from combining with Fenton reaction and unique Janus structure, the phenol in condensed and feed water were removed simultaneously. The removal rate of phenol in the condensed water was as high as 96.2% (4.9 times that of the simple solar interfacial evaporation (19.6%)), and 96.4% in the feed water (10.5 times that of traditional T-type evaporator (9.2%)). The dual-functional evaporator successfully integrated solar interfacial evaporation with advanced oxidation processes (AOPs) to provide a subtlety strategy to solve the problem of pollutant accumulation in long-term water purification and clean water production in solar interfacial evaporation process.