Polyimide-based superhydrophilic porous membrane with enhanced thermal insulation for efficient interfacial solar evaporation

Interfacial solar evaporation (ISE) is a sustainable and efficient strategy to address the freshwater shortage. Herein, we report the fabrication of a novel polyimide-based porous membrane (PI-CB-MHGM) by using synthesized polyamide acid, modified hollow glass microspheres (MHGM), conductive carbon black (CB) and pore-forming agent NaCl particles through spin coating method, followed by hydrophilic modification, and then a bilayer solar evaporator was constructed by using PI-CB-MHGM photothermal membrane as the upper layer and polyurethane (PU) sponge as the bottom layer for ISE. Based on the PI-CB-MHGM photothermal membrane with broadband high light absorption, low thermal conductivity, superhydrophilicity wettability and porous structure, along with the assistance of a porous PU sponge, the as-prepared bilayer solar evaporator exhibits a high evaporation rate of 1.4904 kg m−2 h−1 under 1 sun (1 kW m−2) solar irradiation, as well as excellent evaporation stability and salt resistance. More interestingly, the PI-CB-MHGM membrane possesses self-floating ability, electrical conductivity, superior flexibility, and strong mechanical properties. Furthermore, considering the low cost and simple preparation method, the PI-CB-MHGM based evaporator may hold great potential for a variety of applications, such as, desalination, electricity generation, and wastewater treatment, etc.