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Nearly four billion people worldwide face water scarcity, making atmospheric water harvesting (AWH) a pressing need for decentralized water production. Here, we present carbon dioxide (CO 2 )-activated carbon xerogels engineered with a single-step pyrolysis-activation process following the Boudouard reaction instead of complex, brittle, and expensive frameworks. By varying activation temperature (750–830 °C), time (1–3 h), and particle size distributions, hierarchical porous structures were developed with surface areas >2000 m 2 g –1 that maximized water uptake capacity and cycling efficiency at medium and high relative humidities, without altering surface oxygen-containing functionalities. This material demonstrated a high daily water yield of 43.6 L kg –1 day –1 under 95% RH and 30 °C with 50 stable adsorption–desorption cycles. It possesses fast kinetics, hydrolytic stability, with low-cost scalability (<1 CAD g –1 ) using industrial-grade CO 2 itself as an activation agent. By using a greenhouse gas, this approach establishes an innovative carbon-negative technology for sustainable atmospheric water harvesting for universal access to clean drinking water.
Alavitabari et al. (Mon,) studied this question.