A flexible, high-efficiency, and low-cost FeS₂ @CTS hydrogel film for solar interface water evaporation

Solar interfacial water evaporation to obtain pure water has attracted extensive attention in recent years. In this work, based on the excellent optical property of FeS₂ and the cross-linking nanostructure of chitosan (CTS), a FeS₂ @CTS hydrogel composite film for solar interfacial water evaporation was developed by hydrothermal synthesis and the following composite coating technology. The prepared FeS₂ @CTS presented high solar absorptivity of 95.27% and fast optical response capability. Under the optimized condition, the evaporation rate of pure water reached 3.34 kg m⁻² h⁻¹ and the photothermal conversion efficiency was 103.06% under one sun irradiation. In five runs, the evaporation rate of the FeS₂ @CTS was stable, indicating the excellent cycle stability. Also, in the desalination test, the stable evaporation rate of 1.74 kg m⁻² h⁻¹ was obtained in five runs. Due to the simple preparation method, low cost, and outstanding interfacial evaporation property, this FeS₂ @CTS indicates great potential for the seawater desalination or other photothermal conversion applications.