3D printed thermo-responsive hydrogel evaporator with enhanced water transport for efficient solar steam generation

The development of solar interfacial evaporation technology is of great importance to satisfy the growing clean water demand, while there is still a considerable distance between the existing evaporators and practical applications because of their poor evaporation performance and fouling issues. In this paper, a thermo-responsive evaporator was constructed using 3D printing technology by introducing thermo-responsive poly(n-isopropyl acrylamide) (PNIPAm) into poly(ethylene glycol) diacrylate (PEGDA) and sodium alginate (SA) hydrogels. The prepared evaporator has obvious thermo-responsive behavior with the temperature change around low critical solution temperature (LCST), which significantly facilitates the water-transporting performance of the evaporator. Besides, the high photo-thermal conversion, appropriate thermal conductivity, and high hydrophilicity promote the excellent evaporation performance of the evaporator. Owing to these positive effects, the thermo-responsive evaporator can achieve a high evaporation rate of 3.587 kg·m−2·h−1 under 1.0 kW·m−2 irradiation, which has significant advantages over traditional hydrogel evaporators. Furthermore, good anti-fouling and water purification abilities found in our evaporator promote its practical utilization. This work may pave the way for the development of thermo-responsive solar interfacial evaporators in the application of desalination and water purification.