Engineering of defect–amine coupling in Mg-MOF-74 for boosting CO2 capture

Aminosilane concentration tunes Mg-MOF-74 structural evolution and porosity. • CO 2 adsorption exhibits high uptake at both ambient and high pressures. • The mechanism of how defects and amine groups synergistically enhance CO 2 capture capacity was studied. In this study, we report a rational design and synthesis of hierarchically porous 5/PA2-Mg-MOF-74@APTES with high CO 2 capacity through propionic acid (PA) modulation and amine functionalization (APTES). Characterization results confirmed that an optimized PA concentration effectively induced mesopore formation and exposed more unsaturated Mg 2+ sites, thereby generating hierarchical porosity, while subsequent grafting of APTES successfully introduced amino functional groups This combined strategy leverages both defect engineering and chemical functionalization, synergistically promoting CO 2 adsorption. Performance evaluations revealed that the optimal adsorbent 5/PA2-Mg-MOF-74@APTES(1:1), achieved a CO 2 uptake of 4.91 mmol·g −1 at atmospheric pressure (1 bar) and a remarkable uptake of 17.38 mmol·g −1 at high pressure (15 bar) with significantly improved CO 2 /CH 4 selectivity. This work explores a synergistic enhancement mechanism of CO 2 adsorption from the interplay of defect engineering and amine functionalization conducted by experimental characterization and theoretical calculations, which provides a novel strategy for the design and fabrication of high-efficiency CO 2 adsorbents suitable for diverse pressure applications.