In Situ Growth of Sub-50-nm Zirconium Aminobenzenedicarboxylate Metal-Organic Framework Nanocrystals for Carbon Dioxide Capture.

Controlled synthesis of sub-50-nm metal-organic frameworks (MOFs), which are usually called porous coordination polymers, exhibits huge potential applications in gas storage and separation. Herein, surface-confined growth of zirconium aminobenzenedicarboxylate MOF (UIO-66-NH2) nanocrystals on polypyrrole hollow spheres (PPyHSs) is achieved through covalently grafted benzene dicarboxylic acid ligands using bridged molecules. PPyHSs modified with ligand molecules prohibit excessive growth of UIO-66-NH2 nanocrystals on their confined surface, resulting in smaller-sized nanocrystals (<50 nm) and a monolayer UIO-66-NH2 coating. Benefiting from the homogeneous dispersion of UIO-66-NH2 nanocrystals with a smaller size (40 ± 10 nm), the as-prepared PPyHSs@UIO-66-NH2 hybrids with high specific surface area and pore volume exhibit remarkable CO2 capture performance. Moreover, the time required to reach the maximum CO2 adsorption capacity shortens with decreasing UIO-66-NH2 crystals size. As a proof of concept, the proposed covalent grafting strategy can be used for synthesizing sub-50-nm UIO-66-NH2 nanocrystals for CO2 capture.