In situ growth of the ZIF-8 on the polymer monolith via CO2-in-water HIPEs stabilized using metal oxide nanoparticles and its photocatalytic activity

Here, the ZnO/polyacrylamide (ZnO/PAM) macroporous composite monolith was first prepared through the radical polymerization of acrylamide in ZnO-costabilized CO2-in-water Pickering high internal phase emulsions (HIPEs). An efficient and green synthesis method was used to prepare the ZnO/PAM porous precursor materials, and ZnO nanoparticles (NPs) were used as a metal ion source to grow the metal organic frameworks (MOF) phase through secondary recrystallization, thereby synthesizing the target MOF/PAM porous monolith. The effects of the contents of ZnO NPs on the formation of HIPEs and properties of the target MOF/PAM composites for the photocatalytic degradation of cationic dye were studied. As the content of ZnO NPs increased to 3.75 wt%, the composite monolith had high mechanical stress (0.24 MPa) at 80% strain and recovered their shape. The as-synthesized ZIF-8/PAM composites were characterized using X-ray diffraction, scanning electron microscope (SEM), Brunauer Emmett Teller (BET), energy dispersive X-ray spectrometer (EDS) mapping, and TG methods. SEM images showed that the hybrid materials were interconnected, and the sizes of the open macropore and interconnected pore throats were 30-125 and about 2-20 mu m, respectively. In addition, the ZIF-8/PAM material could be used as a high-efficiency photocatalyst to remove the cationic dye at a fast rate (88.6%).

Automated summary

An efficient and green synthesis method was used to prepare ZnO/PAM porous precursor materials, with ZnO NPs as metal ion source for growing MOF phase to synthesize MOF/PAM porous monolith. Increasing ZnO NPs content improved mechanical stress of the composite monolith, while ZIF-8/PAM material showed high photocatalytic efficiency in dye removal.