Bifunctional core-shell Zr-MOFs@COFs hybrids for CO2 capture and photocatalytic oxidative amine coupling

Herein, the covalent organic frameworks (COFs) were chemically bonded to the surface of the Zr-based metal–organic frameworks (Zr-MOFs), and a series of novel core–shell MOFs@COFs hybrids were prepared. The coating of the COFs not only increases the stability of Zr-MOFs, but also generates new micropores in the interface layer and provides abundant N/S atoms. Additionally, the chemical structure, pore structure, and band gap of the resulting hybrids can be effectively adjusted by changing the monomers of the COFs. The produced hybrid, namely M@COF-SF, exhibits high Brunauer-Emmett-Teller (BET) surface area (1301 m2·g−1), pore volume (0.94 m3·g−1), and heteroatom content (13.38%), endowing it excellent CO2 capture (170 mg·g−1) at 273 K/1.0 bar. Particularly, the introduced thiophene skeleton in the COFs greatly improves the optical properties of the produced hybrid, enabling it to increase the separation performance of electron hole pairs by Z-type electron transfer. Resultantly, it performs well in the photocatalytic oxidative amine coupling with the conversion and the selectivity up to 99%.