Carbon Dioxide Capture in a Carbonate-Pillared Ultramicroporous Metal–Organic Framework

Metal–organic frameworks (MOFs) have emerged as promising candidates for carbon dioxide (CO2) capture due to their ability to tailor pore structures and textural properties with ease. Nevertheless, utilizing low-cost and environmentally benign chemicals as ligand sources is crucial to ensure the sustainable application of MOFs. Herein, we report that Zn2(atz)2(CO3) (atz = 3-amino-1,2,4-triazolate), a carbonated-pillared ultramicroporous MOF that can be synthesized using sodium bicarbonate (also known as "baking soda"), exhibits good CO2 adsorption capacity, achieving 1.9 mmol g–1 at 298 K and 15 kPa. Furthermore, it displays a moderate isosteric heat of adsorption (Qst) for CO2, measuring 37.5 kJ mol–1 at near-zero coverage, with an exceptional ideal adsorbed solution theory (IAST) CO2/N2 selectivity of 188 for a 15/85 (v/v) CO2/N2 mixture at 298 K and 100 kPa. Remarkably, our breakthrough experiments under both dry and humid conditions reveal that Zn2(atz)2(CO3) maintains its CO2 capture capabilities, even at intermediate relative humidity levels (e.g., 40%). Intriguingly, Monte Carlo and dispersion-corrected density functional theory simulations suggest that carbonate anions, by which zinc-aminotriazolate layers are pillared, significantly interact with the CO2 molecules.