Anion-cation heterostructured hydrogels for all-weather responsive electricity and water harvesting from atmospheric air. (15th December 2022) - Lu, Wanheng
Abstract: Despite the recent boom in moisture-enabled electricity generation (MEG), it suffers from fabrication intricacy and materials inadequacy for water and energy harvesting purposes. Moreover, conventional MEGs face challenges in restricted operating humidity, inertness to subtle humidity fluctuations and inability to sustain long-lasting power output under high humidity due to limitations in hydrophilicity and hydration. Here, we exploit a unique oppositely-charged hydrogel heterojunction for electricity and fresh water harvesting from atmospheric air without trade-offs in process simplicity and humidity limits. This anion-cation heterostructure engages two oppositely polarized ions and features a self-regulating ionic gradient for MEG in a dynamically fluctuating ambient, making it not only capable of responding to sluggish and subtle humidity fluctuations but delivering undisrupted power even under extremely wet conditions. Different from other MEGs, moisture can be captured and largely stored in the hydrogel and then released as fresh water. This moisture absorption/desorption, interestingly, is accompanied by electricity generation, indicating a two-in-one strategy to address the water-energy nexus. In such a hydrogel heterojunction, multiple environmental elements like moisture, light, temperature, wind, etc., are feasibly mobilized for energy harvesting. This work provides a promising autonomous and continuous operation of an energy-water system for sustainable and decentralized purposes. Graphical Abstract: Moisture-enabled electricity and water generator (MEWG) is constructed from hydrogel heterojunctions of two oppositely charged hydrogels to generate green energy and freshwater from atmospheric air. In the moist air, hydrogels capture moisture to their network, making dual counter-ions with opposite polarities dissociate from the hydrogel network to generate continuous power or electricity closely dependent on environmental humidity variations. ga1 Highlights: Without complicated treatments or designs, heterojunctions can output continuous power under 20–100% RH. Under high humidity 90%RH, the power supply can last up to 45 h. Electricity can be generated during both moisture absorption and desorption processes. Heterojunctions can simultaneously harvest energy and water from atmospheric air. Hydrogels can be functionalized as a hybrid system to uninterruptedly harvest multiple low-grade environmental energy.