Fig. 2: Preparation of hydroxide charged-sorbents and CO₂ sorption.

a, Scheme of charging activated carbon fabric ACC-5092-10 cloth in 6 M KOH through a three-electrode configuration. Scale bar, 0.5 cm. b, ¹H solid-state NMR (9.4 T) spectra of PCS-OH and control samples, acquired at a magic angle spinning (MAS) rate of 12.5 kHz. c, CO₂ adsorption (filled data points) and desorption (hollow data points) isotherms of PCS-OH and control samples at 25 °C. d, Low-pressure region of the CO₂ adsorption isotherms from c. e, CO₂ uptake of PCS-OH and control samples at 0.4 mbar and 25 °C. Standard deviations are calculated from ten independent samples for PCS-OH, and three independent samples otherwise. f, Adsorption microcalorimetry measurements of the differential molar adsorption heats curves related to the adsorption of CO₂ at 30 °C on PCS-OH (grey) and blank cloth (green). The dotted horizontal line represents the standard molar enthalpy of liquefaction of CO₂ at 30 °C of −17 kJ mol⁻¹. The inset shows volumetric isotherms obtained by performing CO₂ adsorption at 30 °C on PCS-OH (grey) and blank cloth (green) with the volumetric line coupled to the microcalorimeter. g, Dry, pure CO₂ uptake curves at 40 °C and 1 bar CO₂ for PCS-OH after activation under flowing dry N₂ at 130 °C for 1 h (grey curve), after exposure to flowing dry air (roughly 21% O₂ in N₂) at 100 °C for 12 h (red curve), and after exposure to flowing dry air (roughly 21% O₂ in N₂) at 150 °C for 12 h (blue curve). h, Cycling capacities for 150 adsorption–desorption cycles for the PCS-OH in a simulated temperature–pressure swing adsorption process (Extended Data Fig. 6b). Adsorption 30 °C, 20 min; Desorption 100 °C, 20 min; dry 30% CO₂ in N₂ was used for both the adsorption and desorption steps.