Interfacial solar evaporator with an extended photothermal layer for efficient water-salt-electricity cogeneration

Interfacial solar evaporator with an extended photothermal layer was designed and fabricated. • The unique structure of the evaporator enables simultaneous water-salt-electricity cogeneration. • The evaporation rate and efficiency reach 2.009 kg m -2 h -1 and 99.72% under 1 sun illumination. • In 3.5 wt% NaCl solution, 0.1594 g of salt is recovered with an average output voltage of 283.85 mV. Solar-driven interfacial evaporation (SDIE) represents a highly efficient strategy for sustainable freshwater production and energy recovery. However, conventional evaporators suffer from limited functionality and fail to simultaneously achieve high evaporation efficiency, directional salt crystallization, and efficient energy harvesting. Herein, we designed and fabricated an interfacial solar evaporator with an extended photothermal layer by optimizing the geometry of the water-supply layer. By fully exploiting both the illuminated and shaded sides of the photothermal layer, the evaporator establishes a highly efficient synergistic evaporation mode, thereby significantly boosting the overall vapor generation performance. Moreover, its directional water transport capability endows the evaporator with exceptional stability during saline water evaporation and enables efficient salinity gradient electricity generation. The evaporator achieves an evaporation rate of 2.009 kg m −2  h −1 and an evaporation efficiency of 99.72% under 1 kW m −2 (1 sun) illumination. Concurrently, during continuous desalination of a 3.5 wt% NaCl solution for 8 h, the system achieves directional salt crystallization and effectively recovers 0.1594 g of NaCl crystals. Meanwhile, it delivers an average output voltage of 283.85 mV without impairing the evaporation performance. Under outdoor conditions with an average solar irradiance of 0.5345 sun, the evaporation system exhibits a mass loss of 18.81 kg m −2 , an average output voltage of 750.47 mV and an average current of 197 μA, while maintaining efficient directional salt crystallization. This work provides a promising strategy for the design of high-efficiency water-salt-electricity cogeneration systems. Download: Download high-res image (112KB) Download: Download full-size image