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.

大气中含有 13,000 万亿升水，它是随处可用的自然资源。基于吸附的大气水收集（SAWH）能够使用吸附剂材料在广泛的相对湿度范围内提取水蒸气，为解决世界三分之二人口面临的水资源短缺问题开辟了新途径。尽管已经取得了实质性进展，但基础研究和实际应用之间仍然存在相当大的障碍。在这篇综述中，我们为 SAWH 技术提供了多尺度视角，可以填补多个长度尺度上的现有知识空白。首先，我们阐明分子水平上的水吸附机制、理解吸附剂材料的方法以及水传输现象。凭借微观洞察力，我们将材料创新与设备实现联系起来，讨论增强设备级吸附动力学和传热性能的策略，并表明多尺度设计和优化策略可以为系统热力学极限带来新的机会空间。最后，我们对大规模 SAWH 作为全球水技术的技术经济、社会和环境影响进行了展望。通过将材料与设备连接起来，我们设想这种多尺度视角可以指导下一代 SAWH 技术，并促进对社会和环境产生更广泛的影响。