Abstract
Selective carbon capture from exhaust gas and biogas, which mainly involves the separation of CO(2)/N(2) and CO(2)/CH(4) mixtures, is of paramount importance for environmental and industrial requirements. Herein, we propose an interesting metal-organic framework-based nanotrap, namely ZnAtzCO(3) (Atz(-) = 3-amino-1,2,4-triazolate, CO(3)(2-) = carbonate), with a favorable ultramicroporous structure and electrostatic interactions that facilitate efficient capture of CO(2). The structural composition and stability were verified by FTIR, TGA, and PXRD techniques. Particularly, ZnAtzCO(3) demonstrated high CO(2) capacity in a wide range of pressures, with values of 44.8 cm(3)/g at the typical CO(2) fraction of the flue gas (15 kPa) and 56.0 cm(3)/g at the CO(2) fraction of the biogas (50 kPa). Moreover, ultrahigh selectivities over CO(2)/N(2) (15:85, v:v) and CO(2)/CH(4) (50:50, v:v) of 3538 and 151 were achieved, respectively. Molecular simulations suggest that the carbon atom of CO(2) can form strong electrostatic C(δ+)···(δ-)O-C interactions with four oxygen atoms in the carbonate ligands, while the oxygen atom of CO(2) can interact with the hydrogen atoms in the triazolate ligands through O(δ-)···(δ+)H-C interactions, which makes ZnAtzCO(3) an optimal nanotrap for CO(2) fixation. Furthermore, breakthrough experiments confirmed excellent real-world separation toward CO(2)/N(2) and CO(2)/CH(4) mixtures on ZnAtzCO(3), demonstrating its great potential for selective CO(2) capture.