The assembly of novel Ag-based NP@MOFs mesoporous spherical composites and their enhanced catalytic performance in photodegradation and chemical conversion of CO2 with epoxide

Polystyrene microspheres with carboxyl functional groups have been used as template for the controlled synthesis of mesoporous NH2-MIL-101(Cr) spherical shell (NH2-MIL-101(Cr)-s) with open pore, and silver nanoparticles (Ag NPs) are uniformly loaded on its surface by the coordination of the sulfhydryl groups with the silver ions, and the size of the silver particles can be controlled with the additional confinement of mesopores. The synthesized composites were characterized and tested for its photocatalytic properties and catalytic performance for the reaction of carbon dioxide with epichlorohydrin to produce cyclic carbonate. The results show that the composite catalysts have better photodegradation effect than pure NH2-MIL-101(Cr)-s and Ag NPs. This is mainly because Ag NPs modification of NH2-MIL-101(Cr)-s promotes charge separation and provides more active reaction sites. Furthermore, NH2-MIL-101(Cr)-s displays good catalytic performance for carbon dioxide addition reaction with epichlorohydrin, and the catalytic effect is further improved after loading Ag NPs. The spherical shell-shaped NH2-MIL-101(Cr)-s has the flexible shell and the mesopores, which can effectively promote the accommodation and diffusion of substrates of various sizes to reach more active sites.