Preparation Of Porphyrin Sensitized Three Layers Magnetic Nanocomposite Fe₃O₄@SiO₂@TiO₂ As An Efficient Photocatalyst

It's very important to reduce the probability of carrier recombinatio,and extend the life of photogenic charge in the TiO₂ research.The band gap width of TiO₂?3.0-3.2eV?not only affects its catalytic performance,but also affects its utilization of sunlight,which hinders the further development of TiO₂.Nano-TiO₂ particles have good dispersion and photocatalytic activity due to their unique nanometer effect.However,nano-TiO₂ was difficult and costly to separated from water.We hope to find the ideal photocatalyst which meet requirements of sustainable development.We synthesized core-shell nanocomposites Fe₃O₄@SiO₂@TiO₂?FST?,and it functionalizedwithcarboxylgroup.Thenitsensitizedbygrafting5,10,15,20-meso-tetra-?para-amino?-phenyl-porphyrin?TAPP?to obtain FST-g-TAPP.FST-g-TAPP has a large pore volume,high thermal stability,and it significantly improved the photocatalytic activity of Fe₃O₄@SiO₂@TiO₂.Besides,it was easy to recycle.A composite material coated with the thermally sensitive polymer?FST-g-TAPP@PNIAPM?was synthesized by introducing double bond on the surface of FST-g-TAPP.And AIBN was used as initiator to initiate the polymerization of monomer NIPAM.FST-g-TAPP@PNIAPM has good dispersion and high stability,which not only solves the problem of magnetic particles tend to aggregate in solution,but also can be recycled by magnetism and temperature.The structure,morphology and stability of products were characterized by FT-IR,¹H NMR,SEM,N₂ adsorption/desorption isotherm,XRD and other methods.In addition,the photocatalytic degradation of rhodamine B?RhB?and methylene blue?MB?was used to study the catalytic performance and the reuse stability of Fe₃O₄@SiO₂@TiO₂,FST-g-TAPP and FST-g-TAPP@PNIAPM.The results showed that TAPP has good sensitization and PNIPAM can prevent nanocomposite from aggregation.FST-g-TAPP and FST-g-TAPP@PNIAPM has excellent photocatalytic activity and reuse stability under visible light irradiation.Finally,the degradation mechanism of the catalyst system was proposed.