Boosting Solar-Driven Water Evaporation through Selective Water Gating Enabled by Thermo-Responsive Sporopollenin

Abstract Solar-driven evaporation has emerged as a sustainable approach for water generation and purification. However, the undesirable heat loss leads to low energy conversion efficiency that limits water generation and impedes the scalability of this technology. Here, we developed a bilayer-structured solar evaporator (SDWEs) by engineering the fluidic flow within two water transport channels. A porous polydopamine (PDA) coating layer served as photothermal section and water supply microchannels, while the thermo-responsive sporopollenin layer on the bottom skeleton of the foam acted as a switchable water gating layer. Through confocal laser microscopy and micro-CT characterization, we demonstrated that this structural design enabled the selective and directional water transport. Noteworthy, this unique fluidic flow could facilitate the continuous supply of thin water layers and reduce the latent heat required for water evaporation. Therefore, the optimized p-SDWE sample achieved a high-water evaporation rate of 3.58 kg m−2 h−1 using 93.9% solar energy from 1 sun irradiation, and successfully delivered 18–22 liters of purified water per square meter of SDWE per day when treating brine water. This work elucidated the functions of water transport at the interface within the solar evaporator and presented a novel strategy for high-performance solar-driven water generation.