Hierarchical Porous Spongy Hydrogel Evaporator with Mechanical Stability and Salt Resistance for Efficient Solar-Driven Desalination

Amid escalating freshwater shortages, green and sustainable technologies that enable efficient water production are attracting growing research interest. Herein, a porous spongy hydrogel-based solar-driven interfacial evaporator (PSPM) capable of efficient photothermal evaporation is developed. The material features a multiscale porous architecture engineered through the synergistic integration of air templating, ice-crystal templating, PNIPAm-induced phase separation, and a salting-out process. Incorporation of MXene nanosheets further enhances the photothermal conversion efficiency. The PSPM demonstrates outstanding mechanical stability, high solar absorption (96%), and a high evaporation rate of 3.32 kg m–2 h–1, with an energy conversion efficiency of 93%. More importantly, the nanoscale anion water channels and microscale water channels suppress salt crystallization. In addition, outdoor evaluations further confirm the PSPM’s high freshwater yield and practical applicability in agriculture, underscoring its potential as an integrated platform for solar-driven seawater desalination to address global water challenges.