Porous biomass foam of polypyrrole-coated cattail fibers for efficient photothermal evaporation

Solar-driven interfacial water evaporation has become a prospective approach for freshwater production, desalination, and sewage treatment via efficient photothermal conversion. Nevertheless, the development of high-performance, low-cost and environment-friendly solar evaporator is still a major challenge. In this work, a three-dimensional porous solar evaporator is proposed based on polypyrrole (PPy) decorated cattail fiber (CF) foam. The CF foam exhibits superior water transport capacity owing to the unique grooved structure of the cattail fiber. The as-prepared PPy@CF foam shows low thermal conductivity, good salt resistance, and superior light absorption of ∼97% in a wide wavelength region (300–2500 nm) after the introduction of PPy coating. The PPy@CF foam exhibits a vapor evaporation rate of 1.678 kg m −2 h −1 as well as a photothermal conversion efficiency of 99.6% under one sun illumination. In addition, the PPy@CF foam may be applied for clean water production from seawater and sewage with prominent rejection of ions and dye. The present work demonstrates the excellent potential of the PPy@CF foam as an economical biomass material for high-performance solar evaporators.