Synthesis of core-shell Fe3O4@SiO2@mesoporous TiO2 and its photoelectrocatalysis degradation of organic pollutants in water

To realize the practical application of solar photocatalysis and photoelectrocatalysis degradation of pollutants， the efficient， stable， and easily separable catalysts should be studied. Fe3O4@SiO2@mesoporous TiO2 （FST） composite photoelectrocatalysts were prepared by sol-gel and hydrothermal methods. The successful synthesis of nano FST was confirmed by characterization analysis. Fe3O4， SiO2， and TiO2 nanoparticles were coated layer by layer with a unique core-shell structure. The FST catalyst can be easily separated from the suspension under the applied magnetic field. The surface photocurrent response and impedance test results of FST show that its activity is significantly enhanced. The photoelectrocatalysis degradation of other organic pollutants under visible light is investigated using the synthesized FST， the 90 min photoelectrocatalysis degradation rates of methylene blue， rhodamine B， methyl orange， and amoxicillin are 98%， 95%， 92%， and 90%， respectively. The main active species capture experiments show that FST produces a large amount of h+ and ·OH through photoelectrocatalysis coupling， which degrades pollutants into CO2， H2O， and inorganic ions.