Photocatalytic performance of TiO2 co-doped with metal organic framework and g-C3N4
TiO2-g-C3N4-ZIF-67 photocatalysts were prepared by co-doping graphite-like phase carbon nitride(g-C3N4)and dimethylimidazole cobalt(ZIF-67)with TiO2 using sol-gel and high temperature calcination method using tetrabutyl titanate,melamine,dimethylimidazole and Co(NO3)2·6H2O as raw materials,and then characterized by XRD,XPS,SEM,and ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS).The photocatalytic activity of TiO2-g-C3N4-ZIF-67 on Methyl Orange degradation was evaluated,with the catalytic mechanism speculated.The results showed that TiO2-g-C3N4-ZIF-67 contained both anatase and a small amount of rutile-phase TiO2,g-C3N4 and ZIF-67.The addition of g-C3N4 decreased the bandgap of TiO2 to 2.45 eV,while the addition of ZIF-67 further reduced it to 1.91 eV,which significantly increased the visible light absorption range of TiO2(492～649 nm).Meanwhile,TiO2-g-C3N4-ZIF-67 formed a typeⅡheterojunction,and the combination of TiO2-g-C3N4 with metal-organic framework enhanced the photocatalytic degradation of Methyl Orange,with TiO2-g-C3N4-ZIF-67-2 with Co mass fraction of 21.5%exhibiting the best photocatalytic performance of degradation rate reaching 79.92%at 40 min of visible light illumination and 58.86%(90 min)after three cycles,showing good stability of catalyst.The photocatalytic reaction had an effect on the crystallinity of the ZIF-67,thus affecting the photocatalytic activity during the cycles.
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