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|a Water pollution can be treated through the photocatalytic reaction of TiO2 or TiO2 com-pounds. A solvothermal method was used to prepare Fe3 O4 and Fe3 O4 @TiO2 composite photocatalyst with (001) high-energy facets exposed in the anatase phase. TiO2 and Fe3 O4 @TiO2 were characterized by field emission scanning electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, X-ray diffraction spectroscopy and Raman spectroscopy. It was found that the composite Fe3 O4 @TiO2 can reduce the band gap and maintain a certain proportion of (001) high-energy facet exposure. The band gaps of Fe3 O4 @TiO2 and TiO2 are 2.5 eV and 2.9 eV, respectively. The exposure percentages of (001) facets of Fe3 O4 @TiO2 and TiO2 are about 25.2% and 12.1%, respectively. Fe3 O4 @TiO2 was used for photocatalytic degradation of Acid Red 73, and it was found that Fe3 O4 @TiO2 could improve the efficiency of photocatalytic degradation of Acid Red 73. The photocatalytic degradation rates of Fe3 O4 @TiO2 and TiO2 at 24 min were 93.56% and 74.47%, respectively. The cycle experiment of photocatalytic degradation of Acid Red 73 by Fe3 O4 @TiO2 showed that at the fifth cycle, the rate of dye degradation decreased to 77.05%, but the rate of dye degradation can reach more than 90% after self-cleaning treatment. The photocatalytic degradation mechanism is explained by the energy band theory and the first-order kinetic equation model. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
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