Amine‐Functionalized Triazolate‐Based Metal–Organic Frameworks for Enhanced Diluted CO2 Capture Performance

Abstract Efficient CO 2 capture at concentrations between 400–2000 ppm is essential for maintaining air quality in a habitable environment and advancing carbon capture technologies. This study introduces NICS‐24 (National Institute of Chemistry Structures No. 24), a Zn‐oxalate 3,5‐diamino‐1,2,4‐triazolate framework with two distinct square‐shaped channels, designed to enhance CO 2 capture at indoor‐relevant concentrations. NICS‐24 exhibits a CO 2 uptake of 0.7 mmol/g at 2 mbar and 25 °C, significantly outperforming the compositionally related Zn‐oxalate 1,2,4‐triazolate – CALF‐20 (0.17 mmol/g). Improved performance is attributed to amino‐functions that enhance CO 2 binding and enable superior selectivity over N 2 and O 2 , achieving 8‐fold and 30‐fold improvements, respectively, in simulated CO 2 /N 2 and CO 2 /O 2 atmospheric ratios. In humid environments, NICS‐24 retained structural integrity but exhibited an 85 % reduction in CO 2 capacity due to competitive water adsorption. Breakthrough sorption experiments, atomistic NMR analysis, and DFT calculations revealed that water preferentially adsorbs over CO 2 due to strong hydrogen‐bonding interactions within the framework. Gained understanding of the interaction between CO 2 and H 2 O within the MOF framework could guide the modification via rational design with improved performance under real‐world conditions.