Figure 2.

a. Fourier transform‐infrared (FT‐IR) attenuated total reflectance (ATR) spectra during CO₂ adsorption for p(CO₂)=0.02 bar to 0.75 bar into PCN‐222, PCN‐223 and TCPP, focusing on the ν(C=O) band region. Spectra were obtained with volume fractions of 2 %, 5 % and 13 % of PCN‐222, PCN‐223 and TCPP. Gas‐phase CO₂ bands were subtracted to evidence adsorbed CO₂ signals. b. CO₂ sorption capacity for PCN‐222, PCN‐223 and TCPP derived from the ν_as(C=O) band areas as function of applied CO₂ concentration. c. FT‐IR ATR spectra of the Zr−OH bands region at p(CO₂)=0.75 bar, showing a shift in the Zr−OH band of 30 cm⁻¹, while no changes are visible for TCPP (background recorded at p(CO₂)=0 bar).