Recent Development of Atmospheric Water Harvesting Materials: A Review

Abstract

The lack of freshwater has been threatening many people who are living in Africa, the Middle East, and Oceania, while the discovery of freshwater harvesting technology is considered a promising solution. Recent advances in structured surface materials, metal–organic frameworks, hygroscopic inorganic compounds (and derivative materials), and functional hydrogels have demonstrated their potential as platform technologies for atmospheric water (i.e., supersaturated fog and unsaturated water) harvesting due to their cheap price, zero second energy requirement, high water capture capacity, and easy installation and operation compared with traditional water harvesting methods, such as long-distance water transportation, seawater desalination, and electrical dew collection devices in rural areas or individual-scale emergent usage. In this contribution, we highlight recent developments in functional materials for “passive” atmospheric water harvesting application, focusing on the structure–property relationship (SPR) to illustrate the transport mechanism of water capture and release. We also discuss technical challenges in the practical applications of the water harvesting materials, including low adaptability in a harsh environment, low capacity under low humidity, self-desorption, and insufficient solar-thermal conversion. Finally, we provide insightful perspectives on the design and fabrication of atmospheric water harvesting materials.

Biomimetic Dual Absorption–Adsorption Networked MXene Aerogel-Pump for Integrated Water Harvesting and Power Generation System

“…As an integral part of the earth's ecosystem, water, namely water vapor, is widely distributed in nature, enabling various important processes to be realized, from microbial growth to the hydrological cycle. 1 Thus, how to control the moisture or water is very important for human kind because: (1) many people are suffering from water scarcity in arid regions; 2 (2) oppositely, high humidity could cause certain harm to the human body. 3 To date, the utilization of these transformative technologies has regrettably been considerably restricted, particularly in underdeveloped and inland regions, primarily due to their exorbitant costs and limited water transportation capacity.…”

Overview of the design of bionic fine hierarchical structures for fog collection

“…and makes up only 2.8% of the Earth. 1–4 Also, the freshwater distribution is unbalanced due to the variation in climate and geographic location. Presently, around two-thirds of the world's population has limited access to freshwater for at least one month of the year.…”

Harvesting of Atmospheric Water Using Polymer‐Based Hybrid Hydrogels

“…For atmospheric water harvesting, which includes unsaturated water and supersaturated fog, recent developments in functional hydrogels, polymer-supported nanomaterials, hygroscopic inorganic compounds, and metal-organic frameworks have shown their potential as platform technologies due to their low cost, low energy demand, and excellent water retention capacity (Fig. 2), in contrast to conventional means of harvesting water methods, like water transportation to distant areas, desalination, and dew collecting systems using electrical devices [32].…”

“…Schematic illustration of different types of highly functional nanomaterials employed for unsaturated and saturated atmospheric water harvesting. Reproduced with permission from 32.…”