Biomass derived Janus solar evaporator for synergic water evaporation and purification

Solar steam generation has been regarded as an environment-friendly strategy to mitigate the worldwide freshwater shortage. Challenges remain in terms of high-cost of raw materials, complicated fabrications and inability to scale up. Here, an all biomass loofah-derived evaporator composed of a porous supporter (alkalized loofah sponge) and light absorber (carbonized loofah sponge) for highly efficient solar steam generation is proposed, which employs synergistic concepts of solar evaporation and surface biosorption for simultaneous generating freshwater and recycling heavy-metal ions. This multifunctional photothermal evaporator shows an excellent evaporation rate of 1.36 kg m−2 h−1 and corresponding light-to-vapor energy conversion efficiency of 83.7% under 1.0 Sun, and simultaneously delivers excellent self-desalting performance. The developed photothermal evaporator derived from biomass loofah is promising for low-cost and large-scale freshwater production for the water-stressed regions.