Quick Release Anti-Fouling Hydrogels for Solar-Driven Water Purification

Hydrogels are promising soft materials for energy and environmental applications, including sustainable and off-grid water purification and harvesting. A current impediment to technology translation is the low water production rate well below daily human demand. To overcome this challenge, we designed a rapid-response, antifouling, loofah-inspired solar absorber gel (LSAG) capable of producing potable water from various contaminated sources at a rate of ~ 26 kg m^-2 h^-1, which is sufficient to meet daily water demand. The LSAG—produced at room temperature via aqueous processing using an ethylene glycol (EG)-water mixture—uniquely integrates the attributes of poly(N-isopropyl acrylamide) (PNIPAm), polydopamine (PDA), and poly (sulfobetaine methacrylate) (PSBMA) to enable off-grid water purification with enhanced photothermal response and the capacity to prevent oil- and bio-fouling. The use of the EG-water mixture was critical to forming the loofah-like structure with enhanced water transport. Remarkably, under various sunlight irradiations of 1 and 0.5 sun, LSAG required only 10 to 20 min to release ~ 70 % of its stored liquid water, respectively. Equally important, we demonstrate the ability of LSAG to purify water from various harmful sources, including those containing small molecules, oils, metals, and microplastics.