Water strider inspired floating solar evaporator with high salt-resistant ability for desalination of contaminated seawater

Abstract

Solar-driven interface desalination (SDIE) is a low-energy-cost method to address freshwater and energy crises. Unfortunately, not only salt accumulation but also current seawater desalination seriously impairs steam generation and limits long-term use of the evaporator. Moreover, the pathogens and organic contamination severely threatens the production of drinkable water. Herein, we constructed a salt-resistant solar evaporator based on hierarchical FeS2/TiO2 nanotube arrays (FeS2-TNTs) with an assembled Ti mesh. Inspired by the floating feature of water striders, a hydrophobic coating was constructed at the four corners of the mesh, and the gap created by the microstructure offered a unique salt excretion pathway and addressed the salt accumulation challenge. The resulting self-floating mesh achieved a high evaporation rate of 1.05 kg m−2 h−1 in 20 wt% NaCl solution and stably applied for more than 20 days without salt accumulation under 1-sun irradiation. In addition, because of excellent photo-Fenton catalytic performance of FeS2/TiO2 heterostructure, the evaporator effectively removed more than 90% of organic pollutants, including volatile organic compounds (VOCs), dyes, antibiotics, and pesticides in 30 min and inactivate 107 CFU mL−1 of Escherichia coli (E. coli) within 20 min in a simulated seawater without salt accumulation under 1 sun. The salt-resistant evaporator is easily scalable and tailorable, providing a promising solar desalination device for water purification with a low energy cost.