Porifera-inspired cost-effective and scalable “porous hydrogel sponge” for durable and highly efficient solar-driven desalination

Hydrogel evaporator is becoming an excellent platform for solar-driven water purification. However, the cost effectiveness and scalability of hydrogel-based evaporate materials is still a great challenge due to the high energy-consuming and time-consuming freeze drying process, as well as limited black hydrogel materials. Herein, inspired by porifera, “porous hydrogel sponge” has been proposed and realized via in-situ growth of novel adhesive/black hydrogel on polyurethane (PU) sponge without freeze drying process for durable and highly efficient solar-driven water evaporation. The in-situ generated hydrogel can firmly adhere on the sponge skeleton just like a skin, and the thickness of the hydrogel layer can be readily controlled to reserve the high porosity of the sponge, while the sponge skeleton can endow the evaporator with desirable mechanical stability (can be arbitrarily compacted, folded, and twisted). The water evaporation rate of the resultant hydrogel evaporator can reach up to 2.8 kg m-2h−1 under one sun with excellent cost-effectiveness at 332 g h−1 $−1. Moreover, the resultant hydrogel evaporator possesses outstanding long-term cycling stability (at least 6 months), and can be as large as 7500 cm2 (can be readily enlarged further). This study represents a new avenue for fabrication and design of high performance hydrogel evaporator toward practical application, and will contribute to the global effort in addressing world water and energy issues.