Selective confinement of KOH within activated carbon cloth: A strategy for fast, low-temperature regenerable direct air capture

Selective confinement of KOH in micropores eliminates surface KOH aggregation. • Fast kinetics and low-temperature regeneration (80–100 °C). • 89% capacity retention over 50 cycles with active species stably locked in micropores. • Confined water enables dry-air chemisorption with fully reversible humidity tolerance. Direct air capture (DAC) of CO 2 requires sorbents that combine high uptake, fast kinetics, and low-energy regeneration. Here, we report a selective confinement strategy to fabricate a KOH-functionalized activated carbon cloth (KOH-O-ACC) that achieves these goals, delivering both fast adsorption kinetics and low-temperature regenerability. By selectively removing surface-deposited species while preserving KOH confined within the micropores, this approach shifts the active species from undesirable surface accumulation into the micropores. The resulting sorbent delivers a CO 2 uptake of 0.358 mmol/g under realistic DAC conditions (400 ppm CO 2 , 30 °C) and can be regenerated at low temperatures of 80–100 °C. Over 50 adsorption-desorption cycles, the material retains approximately 89% of its initial capacity and exhibits superior oxidative stability compared to amine-based sorbents. Preliminary mechanistic insights suggest that the strong chemisorption under dry conditions may be related to confined water retained within the material. This work demonstrates that precise spatial control of active species is a critical design principle for developing energy-efficient and durable DAC sorbents.