Economical Salt-Resistant Superhydrophobic Photothermal Membrane for Highly Efficient and Stable Solar Desalination

Abstract

Recently, solar-driven interfacial water evaporation has shown great potential in desalination. In a practical application, the inevitable pollution and accumulation of salt that make the evaporation efficient cannot be maintained for a long time. Herein, we report a flexible and economical superhydrophobic photothermal membrane composed of polyvinylpyrrolidone (PVP) and carbon nanotubes (CNTs) with a 1<i>H</i>,1<i>H</i>,2<i>H</i>,2<i>H</i>-perfluorodecyltriethoxysilane modification, with a piece of expanded polystyrene used for support and thermal insulation. The prepared floating evaporation device showed a high energy efficiency of 91.1% and an evaporation rate of 1.41 kg m^-2 h^-1 under one solar irradiation, and neither salt accumulation nor a significant decrease in the evaporation rate of the device was observed after continuous operation for either 40 h or 18 evaporation cycles. In addition, the self-cleaning performance of the membrane enabled its surface to maintain high absorbance for a long time. With the stable and efficient evaporation performance of this device, it provided guidance for the application of efficient and long-term stable solar desalination.