Extended Data Fig. 8: Direct air capture uptake kinetics measured by thermogravimetric analysis.

In (a), data are shown for PCS-OH, 30 °C, 90 mL/min gas flow, 400 ppm CO₂ in air. In (b), data are shown for: PCS-OH (14 months after sample preparation, this work), 30 °C, 90 mL/min gas flow, 400 ppm CO₂ in air. Zn-(ZnOH)₄(bibta)₃ metal-organic framework, 27 °C, 50 mL/min gas flow, 395 ppm of CO₂, 21% O₂, N₂ balance¹⁰. PEI/MMO composite (PEI67/Mg0.55Al-O), 25 °C, 100 mL/min gas flow, 400 ppm CO₂ in N₂³⁶. PEI/SBA−15 composite (PEI67/SBA−15), 25 °C, 100 mL/min gas flow, 400 ppm CO₂ in N₂³⁶. In (c), the data from (b) are plotted in terms of percentage uptake for each sorbent. The results in (b) show that PCS-OH can capture a comparable quantity of carbon dioxide per unit time to literature sorbents for times of approximately 10 to 15 min. Due to the rapid saturation of PCS-OH shown in (c), a relatively short adsorption cycle time should be used for this material. (d) DAC cycling experiments for PCS-OH in the sealed chamber, with 20 min Joule heating regeneration under nitrogen between cycles. The RH during DAC tests was controlled by a desiccant (silica gel) at 11% at 25 °C. The mass of PCS-OH used was 30 mg. The CO₂ capacities in these tests are listed in the figure, and correspond to gravimetric capacities of 0.11, 0.10, 0.10, 0.11, and 0.11 mmol g^–1, respectively.