Water Harvesting with Zeolite, MOF, COF, and HOF Adsorbents

To deal with global water shortage, water vapor in the air is regarded as a freshwater source that cannot be ignored, especially in water-scarce regions. Adsorption-based atmospheric water harvesting (AAWH) is a promising option that utilizes the interaction between the internal structure of the adsorbent material and water molecules to accumulate water. Novel water harvesting adsorbents such as zeolites, metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HOFs) have given new perspectives to fundamentally improve the effectiveness of AAWH, benefiting from their steep S-shaped isotherms. Based on the selection criteria derived from the principle of AAWH, 5 zeolites, 20 MOFs, 6 COFs, and one HOF are identified as potential candidates. From the analysis of the water adsorption mechanisms of these four types of materials and summarizing the latest progress in AAWH devices, the next-generation AAWH technology should focus on the scale-up of well-designed adsorbent components and their integration into efficient system devices to promote the practical application of AAWH.