Highly Efficient and Salt‐Tolerant Broom‐like Bamboo Solar Evaporator: Constructing Multiscale Open Gaps to Enhance Water Transportation and Vapor Diffusion

Solar interfacial evaporation, featuring no extra energy need and low equipment demand, offers a promising off‐grid desalination solution to alleviate global freshwater shortage. However, solar evaporators typically rely on internal pores for water transport that impedes vapor escape. In this work, exploiting a two‐phase structure and directional arrangement of bamboo, a bamboo fiber aggregation (BFA)‐based broom‐like solar evaporator with open fibrous gaps for water transport and vapor diffusion is developed. The polypyrrole‐coated BFA (PPy‐BFA) evaporator exhibits a water evaporation rate of 3.3 kg m −2 h −1 with an efficiency of 146.7% under 1 sun. This value is 2.6 times higher than that of PPy‐coated natural bamboo and superior to most of the previously reported bamboo‐based evaporators. These low‐tortuosity fiber gaps enable rapid water transport while providing extensive air–liquid interfaces that effectively promote vapor diffusion and harness heat from the environment. Open‐channel configuration has a lower surface temperature and more uniform vapor distribution than that of the internal‐channel one, preventing the formation of high‐humidity zones. Moreover, PPy‐BFA also demonstrates excellent salt tolerance performance, maintaining a stable evaporation rate of 2.3 kg m −2 h −1 for 20% NaCl solution. This work offers important insights into the configuration design of solar evaporators and provides a low‐cost choice for off‐grid desalination.