Phase Inversion-Based foam hydrogels for highly efficient Solar-Powered interfacial desalination

Innovative materials are required to promote the development of solar-powered interfacial desalination and purification technologies to address global freshwater scarcities. To this end, evaporators using polymeric hydrogels have been widely studied. However, these systems are slow, energy-intensive, complex, and difficult to operate. New strategies are in urgent need. The present work employs polymeric phase inversion to develop poly (vinyl alcohol) (PVA)-based foam hydrogels, wherein the air bubble phase served as the matrix and cross-linked PVA hydrogel acted as the dispersed phase. In addition, we utilize Ti(3)C(2)Tx nanosheets-based MXene as the photothermal agent to facilitate the fabrication of hierarchical pore-in-pore structures. The prepared PVA/MXene foam hydrogels exhibit > 95% porosity, as well as high compressibility (> 7000 cycles) and very rapid water transport. Importantly, these materials also exhibit remarkably low water evaporation enthalpies. Combined with a new heat supply model, those foam hydrogels achieve an evaporation rate of 4.1 +/- 0.1 kg m(-2)h(-1) with energy efficiency up to 128.8% +/- 2.0% under 1 sun irradiation, which is the highest value for MXene-based nanocomposites reported so far. This study demonstrates a significant advancement in solar desalination sys-tem by combining phase inversion to make innovative foam materials with optimal external heat management.

Automated summary

In order to address global freshwater scarcities, innovative materials are needed for the development of solar-powered interfacial desalination and purification technologies. This study utilizes polymeric phase inversion to develop PVA-based foam hydrogels with high porosity, compressibility, and rapid water transport. These materials also exhibit low water evaporation enthalpies and achieve high evaporation rates and energy efficiency under 1 sun irradiation.