Title High Solar‐Thermal Conversion Aerogel for Efficient Atmospheric Water Harvesting

Abstract

The shortage of freshwater is a global problem, however, the gel that can be used for atmospheric water harvesting (AWH) in recent years studying, suffer from salt leakage, agglomeration, and slow water evaporation efficiency. Herein, a solar‐driven atmospheric water harvesting (SAWH) aerogel is prepared by UV polymerization and freeze‐drying technique, using poly(N‐isopropylacrylamide) (PNIPAm), hydroxypropyl cellulose (HPC), ethanolamine‐decorate LiCl (E‐LiCl) and polyaniline (PANI) as raw materials. The PNIPAm and HPC formed aerogel networks makes the E‐LiCl stably and efficiently loaded, improving the water adsorption‐desorption kinetics, and PANI achieves rapid water vapor evaporation. The aerogel has low density ≈0.12–0.15 g cm−3, but can sustain a weight of 1000 times of its own weight. The synergist of elements and structure gives the aerogel has 0.46–2.95 g g−1 water uptake capability at 30–90% relative humidity, and evaporation rate reaches 1.98 kg m−2 h−1 under 1 sun illumination. In outdoor experiments, 88% of the water is harvesting under natural light irradiation, and an average water harvesting rate of 0.80 gwater gsorbent−1 day−1. Therefore, the aerogel can be used in arid and semi‐arid areas to collect water for plants and animals.

Green Synthesis of Polyurethane Sponge-Grafted Calcium Alginate with Carbon Ink Aerogel with High Water Vapor Harvesting Capacity for Solar-Driven All-Weather Atmospheric Water Harvesting

“…These results further indicated that SCAC has good structural stability. The water absorption performance of SCAC was significantly superior to most of the reported hygroscopic materials (Figure f). ,− Furthermore, the water absorption rate of the hygroscopic agent was an indicator for judging the hygroscopicity. As can be seen from Table S2, the water absorption rate of SCAC was also much higher than that of the other hygroscopic agents in the Table.…”

Solar-Responsive Interface Self-Assembled MOF-Derived Foam for Adaptive Indoor Humidity Regulation

“…Clearly, the optical absorption of C/PU/Al-fumarate across the entire wavelength range (200–2500 nm) was higher than that of PU/Al-fumarate (Figure d). This can be attributed to the black C particles coating the PU skeleton, which induces repeated reflection or scattering of light and absorbs internal light into C/PU/Al-fumarate. , Subsequently, the photothermal conversion efficiency of the samples under simulated solar radiation was demonstrated using an infrared thermography camera. Under one sun radiation intensity (100 mW cm –2 ), the maximum surface temperature of C/PU/Al-fumarate reached 72.1 °C (Figure e), which is significantly higher than that of PU/Al-fumarate (40.7 °C).…”

Macroporous, Highly Hygroscopic, and Leakage-Free Composites for Efficient Atmospheric Water Harvesting

“…Moreover, the AWH efficiency of such composites is usually increased with increasing the fraction of hygroscopic salts. ,, Due to the polyelectrolyte effect, however, quite a small amount of hygroscopic salt could be loaded into nonionic hydrogels or cellulose aerogels because an increase in the salt concentration decreased the osmotic pressure between the solution and the hydrophilic networks. − The relatively low fraction of hygroscopic salt limits the moisture adsorption capacity and thus the efficiency for AWH. To enhance the hygroscopic salt fraction within composites, hydrophilic networks with porous structures have been developed for hygroscopic composite fabrication . For these composites, however, upon adsorption, the resulting salt aqueous solution tends to leak from the hydrogel because the hydrophilic networks cannot contain so much solution, again imposed by the polyelectrolyte effect.…”

“…To enhance the hygroscopic salt fraction within composites, hydrophilic networks with porous structures have been developed for hygroscopic composite fabrication. 29 For these composites, however, upon adsorption, the resulting salt aqueous solution tends to leak from the hydrogel because the hydrophilic networks cannot contain so much solution, again imposed by the polyelectrolyte effect.…”