Super Atmospheric Water Harvesting Hydrogel with Alginate Chains Modified with Binary Salts

Atmospheric water harvesting is considered to be a promising technology to address the global water shortage. However, researchers are still searching for optimized desiccants with all of the desired features, such as high water sorption capacity, low desorption temperature, wide light spectrum absorption, ease to scale up, and low cost. Here, we modified sodium alginate by occupying both G-blocks and M-blocks with more hydrophilic cations (i.e., Li and Ca). Functionalized carbon nanotubes (FCNTs) are embedded in the hydrogel structure to increase solar spectrum absorption. In summary, these features enable binary composite to adsorb similar to 5.6 g of water per gram of desiccant. For the first time, the idea of rational combination of a binary hydrophilic polymeric salt was embodied. We believe that this binary/FCNT sorbent is a promising material for application in water sorption-based technologies.