Amine‐functionalized Triazolate‐based Metal–Organic Frameworks for Enhanced Diluted CO2 Capture Performance

Efficient CO2 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 CO2 capture at indoor‐relevant concentrations. NICS‐24 exhibits a CO2 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 CO2 binding and enable superior selectivity over N2 and O2, achieving 8‐fold and 30‐fold improvements, respectively, in simulated CO2/N2 and CO2/O2 atmospheric ratios. In humid environments, NICS‐24 retained structural integrity but exhibited an 85 % reduction in CO2 capacity due to competitive water adsorption. Breakthrough sorption experiments, atomistic NMR analysis, and DFT calculations revealed that water preferentially adsorbs over CO2 due to strong hydrogen‐bonding interactions within the framework. Gained understanding of the interaction between CO2 and H2O within the MOF framework could guide the modification via rational design with improved performance under real‐world conditions.