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