Robust, floatable, steam generator based on the graded porous polyimide film for efficient solar desalination

Solar-driven seawater desalination is an environmental friendly technology that could relieve global water shortage. However, the practical applications of solar steam generating devices have been limited by the high energy consumption in the manufacturing process, low durability, and difficulties in large-scale production had limited. Herein, we designed and prepared a polyimide film coated with polypyrrole with graded porous structures (PPy@PI).The photothermal PPy@PI has excellent mechanical properties and thermal stability and requires no nondegradable supporting polymer foam to float in water, making it ideal for desalination applications. Importantly, PPy@PI-S prepared by single-sided deposition of polypyrrole on the surface of the polyimide film has high light absorption capacity (93.57%) and low thermal conductivity under wet conditions (0.3641 W m −1 k −1 ). Under the irradiation of 1 sun (1 kW m −2 ), the evaporation rate was up to 1.23 kg m −2 h −1 corresponding to a solar energy conversion rate of 84%.The simple preparation process enables large-scale preparation of PPy@PI.