Scalable sulfonated activated carbons as high-capacity sorbents for atmospheric water harvesting

We report the synthesis of sulfonated activated carbons capable of direct capture of water from air at relative humidities as low as 10% and temperatures of up to 45 °C. Sulfonated activated carbons are produced via solvent-free sulfonation using only activated carbon and neat sulfuric acid, two abundant and widespread industrial materials. The resulting materials are rapidly accessible, easily scaled, and exhibit excellent water sorption, achieving a total uptake capacity of >1.4 g·g -1 and 0.28 g·g -1 at just 30% relative humidity, placing them among the best-performing materials to date. Water sorption experiments reveal rapid water adsorption and desorption, enabling numerous cycles in a single day. We scale up production of a sulfonated activated carbon to 1.6 kg and demonstrate long-term cycling stability in a water harvesting device, offering excellent potential for real-world implementation.