ZIF-8/TiO2 Composite Mesocrystals:Preparation and Photocatalytic Activity
Microstructure,particle size and specific surface area of TiO2 are crucial factors influencing its photocatalytic activity.Mesocrystals represent a type of superstructural material formed by inorganic nanoparticles aligned along a common crystallographic axis,holding significant research potential in the field of photocatalysis.This study employed ammonium hexafluorotitanate and boric acid as titanium precursor and fluorine ion scavenger,respectively,and used a blend of anhydrous ethanol and deionized water as reaction medium.NH4TiOF3 mesocrystals precursors were prepared by a facile green method.Subsequently,washing with boric acid solution enabled the transformation of NH4TiOF3 mesocrystals into TiO2 mesocrysals through topotaxial conversion.Ultimately,the TiO2 mesocrystals were functionalized with ZIF-8 nanoparticles,and the photocatalytic degradation activity of the obtained ZIF-8/TiO2 composite mesocrystals was studied.The experimental results shows that ZIF-8 nanoparticles can uniformly nucleate on the surface of TiO2 mesocrystals,resulting in a relatively dense coating layer.ZIF-8/TiO2 composite photocatalyst exhibits a higher specific surface area and a narrower band gap.Meanwhile,the separation efficiency of photogenerated electrons and holes is also improved to a certain extent.Notably,the sample M-TiZIF-2(with addition of 4 mmol Zn(NO3)2)demonstrated superior photocatalytic activity,and achieved a first-order reaction rate of 42-fold that of TiO2 mesocrystals and 16-fold that of pristine ZIF-8 nanoparticles.In conclusion,the synergistic effect of ZIF-8 nanoparticles and TiO2 mesocrystals significantly augments the photocatalytic performance of the ZIF-8/TiO2 composite mesocrystal materials.
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