Plant transpiration-inspired environmental energy-enhanced solar evaporator fabricated by polypyrrole decorated polyester fiber bundles for efficient water purification

Solar steam production is regarded as a potential approach for extracting freshwater from undrinkable water. However, it remains a challenge to acquire a low-cost, salt-resistant, durable and efficient solar evaporator through a simple fabrication process. This work presents a plant transpiration-inspired three-dimensional (3D) solar evaporator fabricated by decorating industrial polyester fiber bundles (PFBs) with inexpensive polypyrrole (PPy). This solar evaporator is named the PPy-PFBs. Intriguingly, PFBs composed of hydrophobic polyester fibers with multiple vertical channels are capable of pumping enough water to the top of the solar evaporator through the capillary effect and storing seven times its mass of water, allowing for salt-resistant. In addition, polyester fiber is resistant to acid, alkali, mildew, and sunlight, making the PPy-PFBs durable. Along with the heat generated from sunlight absorbed by the PPy, the 3D solar evaporator can also gain energy from the environment. Adjusting the exposure height and arrangement of PPy-PFBs can control the evaporation rate. The matrix arranged PPy-PFBs with an exposure height of 6 cm attains a high water evaporation rate of 3.77 kg m−2 h−1 with an energy conversion efficiency of 155.77%. Outdoor experiments demonstrate that the PPy-PFBs can extract freshwater from non-drinkable water. 1 m2 of PPy-PFBs can produce about 26 kg of fresh water per day, which is enough to meet the daily drinking water needs of 10 adults. This low-cost, easily made, salt-resistant, durable and high evaporation rate solar evaporator is appealing to alleviate the global freshwater crisis.