Covalently connected core-shell NH2-UiO-66@Br-COFs hybrid materials for CO2 capture and I2 vapor adsorption

Metal organic frameworks (MOFs)@covalent organic frameworks (COFs) (MOFs@COFs) hybrid materials not only combine the advantages of MOFs and COFs, but the possible synergistic effect at the MOFs-COFs interface can improve the performance of the hybrid materials greatly. Herein, the Br-COFs shell was in-situ grown on the surface of the NH2-UiO-66 core by Schiff-based reaction and a kind of novel covalently connected core-shell NH2-UiO-66@Br-COFs hybrid materials were prepared accordingly. Unique structure was generated at the core-shell interface which could be effectively adjusted by the coating amount of Br-COFs. In particular, abundant ultramicropores were generated at the interfacial layers as compared with NH2-UiO-66 and Br-COFs, and the maximum ultramicropore volume (V-ultra) was up to 0.157 cm(3).g(-1). These produced ultramicropores at the core-shell interface made a great positive contribution to the CO2 capacity and the maximum CO2 capacity of the hybrid materials was measured to be 169.5 mg.g(-1) at 273 K and 1.0 bar, outperformed the corresponding single MOF and COF. Additionally, the highest I-2 vapor uptake of the hybrid materials was determined to be 3.73 g.g(-1) and it increased with the increase of the coating amount of Br-COFs. This work presents the successful regulation of the adsorption performance by the rational fabrication of novel hybrid MOFs@COFs interface.

Automated summary

In this study, a novel core-shell NH2-UiO-66@Br-COFs hybrid material was successfully prepared by growing a Br-COFs shell on the surface of NH2-UiO-66 core. The unique structure generated at the core-shell interface, which could be effectively adjusted by the coating amount of Br-COFs, contributed to the increased ultramicropore volume. These ultramicropores positively impacted the CO2 capacity, surpassing that of the single MOF and COF.