The technology of adsorption/absorption atmospheric water harvesting is characterized by ease of operation, low energy consumption, and represents an effective measure to mitigate the scarcity of fresh water resources. A systematic review of recent research progress in this field is presented and an introduction is provided to the basic principles and main material categories of adsorption/absorption air water extraction technology, as well as a summary of the material placement structure, equipment operation mode, and application field of adsorption/absorption equipment. Adsorption/absorption materials include traditional porous structural materials, hygroscopic salts, and new organic air water intake materials. Currently, significant advancements have been made in enhancing the adsorption performance of materials, broadening their application scope, and reducing the energy consumption required for water absorption and release. Nevertheless, there are still challenges related to poor mechanical properties and incapability to be shaped into profiles for adsorption/absorption materials that necessitate further comprehensive investigation. The adsorption/absorption equipment can be utilized for air-water intake applications through various structural configurations, including flat placement, central axis placement, fold placement, etc. This equipment is capable of operating in either a daily cycle or multiple cycle mode. Apart from directly collecting liquid water, the adsorption/absorption atmospheric water harvesting equipment can also serve as an innovative solution for cultivating ecological farms, thereby offering potential strategies to mitigate regional freshwater resource scarcity and food shortages.

Atmospheric water harvesting is a promising strategy to address the water scarcity in islands. In this work, an activated carbon fiber (ACF) templated hybrid water adsorbent ACF-cobalt(Ⅱ)-ethanolamine (ACF-Co-EA) was fabricated and used to build an ecological farm (Eco-farm) for potential application on tropical coral islands. ACF-Co-EA took the advantage of both the pore structure of ACF and the superabsorbent property of the Co-EA complex, thus, exhibiting superior water harvest capacity over ACF or Co-EA. The equilibrium water adsorption of ACF-Co-EA was 763 ​mg ​g⁻¹ ​at 25 ​℃ and 70% RH (typical environment of tropical coral islands). Under 1 ​kW ​m⁻² simulated solar irradiation, the surface temperature of ACF-Co-EA increased rapidly to 50 ​℃ within 12 ​min and stabilized at 54 ​℃ in 30 ​min because of the superior light absorbance of ACF, which made more than 90% of captured water released. ACF-Co-EA-based Eco-farm could harvest 6.9 ​g ​g⁻¹·day⁻¹ of water to ensure plant growth in the tropical coral islands' environment without any additional energy or water supply. The study provided novel ideas to alleviate the problems of freshwater scarcity and food shortage in the tropical coral islands.