Three-Dimensionally Structured Polypyrrole-Coated Setaria viridis Spike Composites for Efficient Solar Steam Generation

Solar-driven steam generation is a promising technology for the production of freshwater from seawater and polluted water. High water evaporation rates have been achieved via the interfacial heating scheme; however, they are still limited to meet the increasing need for freshwater due to the restricted evaporation area of two-dimensionally (2D) geometrical planar photothermal membranes. Herein, a three-dimensionally (3D) structured solar evaporator is prepared via coating photothermal polypyrrole (PPy) on the spike of Setaria viridis(S. viridis) for highly efficient evaporation. Due to the enlarged evaporation area and open structure for vapor dissipation, the PPy-coated S. viridis spike solar evaporator shows a high water evaporation rate of 3.72 kg m^-2 h^-1 under one sun illumination. The 3D solar evaporator also demonstrates good durability and anti-salt-clogging performance for real-life applications. Furthermore, we show that the 3D solar evaporator demonstrates effective decontamination of saline water, dye-contaminated water, and corrosive water. This work can inspire new paradigms toward developing high-performance solar steaming technologies for effective water purification to address the worldwide crisis of freshwater shortage.