High-yield and scalable water harvesting of honeycomb hygroscopic polymer driven by natural sunlight

Abstract

Many materials have been tailored for sorption-based solar-thermal-driven atmospheric water harvesting (AWH), but AWH devices are still inefficient and unscalable. To close the large gap between materials research and practical application, a hydrogel-based composite sorbent (PCLG) with high adsorption capacity per unit volume has been developed with an optimized honeycomb structure, which has potential applications in global water harvesting. The PCLG sorbent achieves 1.8 g/cm 3 water harvested under 30°C and 30% relative humidity (RH). The optimized honeycomb structure enables 50% water absorption improvement due to better heat and mass transfer performance. In outdoor experiments, our water harvester realizes 2.9 L/m 2 /day of water collected per cycle under natural sunlight. Based on PCLG properties and worldwide weather data, our device can yield up to 6 L/m 2 /day of water. The high adsorption/desorption hydrogel sorbent and scalable atmospheric water harvester offer a solution for efficiently extracting water from the air to relieve the thirsty world. • PCLG is a high-efficiency sorbent suitable for AWH in a wide humidity range • Per unit volume adsorption capacity is proposed as an important indicator for AWH • An integrated device with honeycomb PCLG is designed to improve AWH efficiency • Water production of PCLG-based AWH is predicted to validate its global potential There remains a large gap between atmospheric water harvesting materials development and their practical application. Here, Wang et al. report a hydrogel-based composite sorbent with high adsorption capacity per unit volume, demonstrated to harvest 2.9 L/m 2 /day outdoors under natural sunlight as part of an integrated device with a honeycomb structure.