Preparation Of MOFs-based Composite Photocatalyst And Study On Its Photocatalytic Activity

Metal-Organic Frameworks?MOFs?are a new class of functional materials that are self-assembled by metal ions and organic ligands.MOFs materials have a variety of excellent properties,such as porosity,skeleton support,electron conductivity,well adjustment,etc.Through regulation,MOFs can produce the transfer ability of photogenerated charges,and can also directly introduce ligands and metals with excellent optical activity to produce photocatalytic activity,which has great application prospects in the field of photocatalysis.Ultrasonic stripping method was used to synthesize UMOFNs?Ultrathinning MOFs into two-dimensional?2D?nanosheets?composed of Ni²⁺,Co²⁺and organic ligand terephthalic acid?H₂BDC?.The molecular formula is Ni_xCo_x?BDC?_x?OH?_2x.Further,they coated on Ag₃PO₄ nanoparticles to obtain Ag₃PO₄@UMOFNs core-shell composite photocatalyst.Photoelectrochemical test showed that the rapid transfer of charge of UMOFNs increased the photocurrent by 1.5 times,resulting in an increase in photocatalytic activity.Under visible-light irradiation,the degradation of phenol was100%within 16 min,and the degradation of biphenyl A was 98.9%within 20 min via Ag₃PO₄@UMOFNs?5 wt.%?.These values were 1.6-and 1.8-times higher than Ag₃PO₄,respectively.Quenching experiments and ESR experiments showed that the main active species in the photocatalytic process were·O₂^-and·OH.In a further study,g-C₃N₄ nanosheets were combined with UMOFNs nanosheets by mechanical milling to form g-C₃N₄/UMOFNs?2D/2D?composite photocatalyst that enhanced the H₂ production from water splitting via simulated solar light.The composite catalysts offerred photocatalytic hydrogen production activity that was maximal(1909.02?mol·g^-1·h^-1)when loaded with 3 wt.%UMOFNs.This was 3-fold higher than g-C₃N₄nanosheets and 15-flod higher than bluk g-C₃N₄.The main reason for the significant increase in photocatalytic hydrogen production activity is that the two-dimensional structure of the composite photocatalysts has alarge contact areas,more active sites,short charge transfer path and high carrier separation efficiency.Figure 38;Table 5;Reference 99.