Multipurpose Solar-Thermal Hydrogel Platform for Desalination of Seawater and Subsequent Collection of Atmospheric Water

Clean water collection is the most challenging global issue. Hydrogel platform for producing fresh water from both seawater and the atmosphere holds great promise, but it has been difficult to achieve multifunction and integration with it. Here, we have developed a multipurpose solar-thermal hydrogel (TA-Fe@PAM) that can be used for desalination of seawater and subsequent water collection from the atmosphere by impregnating a polyacrylamide network with an iron-tannin photothermal complex. Rapid solar desalination (∼1.93 kg m–2 h–1) was achieved by TA-Fe@PAM under 1 sun irradiation. During this process, large amounts of deliquescent salts, including CaCl2, MgCl2, KCl, and NaCl, entered the TA-Fe@PAM, forming DS-TA-Fe@PAM, which can then be used to collect water from the atmosphere. DS-TA-Fe@PAM captured ∼1.26%, ∼5.56%, ∼17.32%, and ∼31.02% (w/w) water from the atmosphere within 450 min when the relative humidity was 10%, 30%, 50%, and 70%, respectively. More interestingly, almost 100% captured atmospheric water was collected from the inbuilt solar-thermal DS-TA-Fe@PAM under normal intensity sunlight.