Bridging materials innovations to sorption-based atmospheric water harvesting devices

The atmosphere contains 13,000 trillion litres of water, and it is a natural resource available anywhere. Sorption-based atmospheric water harvesting (SAWH) is capable of extracting water vapour using sorbent materials across a broad spectrum of relative humidity, opening new avenues to address water scarcity faced by two-thirds of the population of the world. Although substantial progress has been made, there is still a considerable barrier between fundamental research and real-world applications. In this Review, we provide a multiscale perspective for SAWH technologies that can fill existing knowledge gaps across multiple length scales. First, we elucidate water sorption mechanisms at the molecular level, approaches to understanding sorbent materials, and water transport phenomena. With microscopic insights, we bridge materials innovations to device realization, discuss strategies to enhance device-level sorption kinetics and heat transfer performance, and show that a multiscale design and optimization strategy can lead to a new opportunity space towards system thermodynamic limits. Finally, we provide an outlook for the technoeconomic, social and environmental impact of large-scale SAWH as a global water technology. By bridging materials to devices, we envision that this multiscale perspective can guide next-generation SAWH technologies and facilitate a broader impact on society and the environment. Harvesting freshwater from the air using water sorption materials is an innovative strategy to address water scarcity. This Review offers a multiscale perspective to design the next generation of sorption-based atmospheric water harvesting technology by bridging materials innovations to device realization and provides practical guidelines to understand its real-world impact.