Solar-powered nanostructured biopolymer hygroscopic aerogels for atmospheric water harvesting

Solar energy powered sorption-based atmospheric water harvesting (AWH) is a novel strategy for obtaining fresh water in water-scarce regions. The major challenge is to design a cost-effective all-in-one solid bulk sorbent that can capture water from air, even when outdoor conditions are cool, dry, and with low-intensity nature sunlight. Here, we report a strategy comprising solution exchange and lyophilization for integrating a lithium chloride hygroscopic agent, a nanofibrillated cellulose hydrophilic skeleton and a graphene solar absorber, to exploit a solar-powered nanostructured biopolymer hygroscopic aerogel (NBHA) for AWH. The intrinsic porous bilayer structure with interconnected micron- and nano-scale channels of NBHA enables it readily absorb moisture (even at a low relative humidity of similar to 18%), has a high-water storage capacity, and requires little energy from natural sunlight for solar-driven light-to-vapor conversion. Liquid water was successfully harvested outdoors in natural sunlight of 0.10-0.56 kW m(-2) using a facile device based on the NBHA. This work provides a convenient, effective, and practical solution for AWH, even in severe environmental conditions.

Automated summary

The study introduces a novel strategy of utilizing solar energy to power a nanostructured biopolymer aerogel for atmospheric water harvesting, which shows high moisture absorption capacity and low energy consumption. This biopolymer can absorb water even at low relative humidity and easily collect liquid water under natural sunlight.