Triazole-Based Metal-Organic Frameworks for CO2 Capture.

Metal-organic frameworks (MOFs) based on triazole have attracted considerable interest as promising porous materials for CO2 capture due to their high surface area, ultramicroporosity, and excellent thermal and chemical stability. Nitrogen-rich triazole ligands contain abundant Lewis basic sites that promote CO2 adsorption via dipole-quadrupole interactions, hydrogen bonding and cooperative interactions with open metal sites. The present review discusses recent developments in the synthesis of triazole-based MOFs, with special emphasis on the relation between structural features and CO2 adsorption performance. The paper reviews different synthetic routes such as solvothermal, hydrothermal, mechanochemical and post-synthetic modification methods and their impact on crystallinity, porosity and scalability. The roles of metal centres, pore confinement and linker functionalization in tuning CO2 uptake, selectivity and adsorption energetics are highlighted. Moreover, the mixed-linker strategies and defect engineering are explored to illustrate the use of the synergistic effect of nitrogen-rich sites and metal nodes for the improvement of the adsorption performance. Still, a number of challenges remain such as achieving an optimal balance between adsorption strength and regenerability, increasing stability in humid and realistic flue-gas conditions, and the development of scalable and sustainable synthesis routes. In summary, triazole-based MOFs provide a versatile platform for the design of high-performance CO2 adsorbents by combining structural robustness with chemically active, nitrogen-rich adsorption environments.