Rape Pollen‐Based Composite Sorbent with Thermo‐Responsive and Photothermal Properties for Atmospheric Water Harvesting

Abstract Sorption‐based atmospheric water harvesting (SAWH) has great potential for clean water acquisition and renewable energy use. Adsorption and desorption properties of sorbents play a crucial role in SAWH systems. However, most sorbents with high adsorption capacities are hindered by either slow sorption/desorption kinetics or poor regeneration performance. Here, a highly efficient block copolymer composite sorbent with dual functions of thermo‐responsive and photothermal properties is designed based on rape pollens. This sorbent has a hierarchical porous structure, in which the outermost layer of poly‐pyrrole enables it to convert light energy into heat and the second layer of poly(N‐isopropylacrylamide) imparts thermo‐responsive properties to improve the desorption ability. Meanwhile, confined LiCl improves its sorption capacity and cavities of the pollen can store captured moisture to avoid liquid leakage. This sorbent can sorb moisture to more than 144% of its own weight within 3 h under 20 °C&80% relative humidity (RH) and 82% of captured water can be released within 0.5 h under 1 sun. The water harvester using this sorbent can realize an exceptional water productivity of up to 2.21g_water g_sorbent⁻¹ day⁻¹ only by three continuous water adsorption‐desorption cycles in a day. The high‐performance sorbent smooths the path for efficiently extracting water from the atmosphere to tackle water scarcity.