A Hydroscopic Indium Hydrogel Capturing Atmospheric Humidity for Autonomous Agriculture

Abstract

The atmospheric water is ubiquitous and abundant, which can be effectively exploited for various applications. However, limited efforts are devoted to agriculture due to the slowly capture kinetics and highly dehydration temperature. Herein, benefiting from a super hygroscopic hydrogel, a self‐sustainable atmospheric water irrigation system for plant growth at arid land is integrated. The hydrogel harvests water from the air during the nighttime and efficiently releases adsorbed water when the system is exposed to sunlight. The water capture behavior by hydrogel mainly relies on physisorption, multilayer moistures can be accumulated under weak Van der Waals force. With the help of hydrophilic surface, the indium hydrogel has a maximum water uptake of up to 5.5 g g−1 at 90% relative humidity. This hydrogel induces a >40 °C surface temperature under AM 1.5 G solar illumination, which is enough for water releasing, making the solar energy‐driven water recycling possible. Finally, the collected water quality meets the international drinking water standard, resulting in a rapid growth of pea over 6 cm within 8 days.