Fabrication of magnetic quantum dots modified Z-scheme Bi₂O₄/g-C₃N₄ photocatalysts with superior hydroxyl radical productivity for the degradation of rhodamine B

The kernel of photocatalytic technology is to exploit photocatalytic materials with high efficiency, stability and easy recovery. Herein, we designedly prepare a magnetic quantum dot (Fe₃O₄ QDs) as co-catalyst to modify Z-scheme Bi₂O₄/g-C₃N₄ (Bi/CN) composite photocatalyst via combining calcination with hydrothermal method. The morphology, chemical composition and physicochemical properties of photocatalysts are systematically analyzed by a series of characterization means. The experimental results explicitly render that the optimum Fe₃O₄-QDs/Bi₂O₄/g-C₃N₄ (FeQDs/Bi/CN) has outstanding photocatalytic performance than that of Bi₂O₄, g-C₃N₄ and Bi₂O₄/g-C₃N₄ (Bi/CN), which is chiefly imputed to the synergistic effect of Z-scheme heterojunction system and Fenton reaction. The Z-scheme heterojunction is conductive to accelerate charge carrier separation and makes electrons and holes retain higher redox ability. Fe₃O₄ QDs can promote visible light absorption and generate more hydroxyl active ([rad]OH) substances through Fenton reaction. Furthermore, the magnetic photocatalyst is liable to separate under the action of external magnetic field, which ensures that is convenient for industrial application. The mechanism of photocatalytic degradation is discussed in detail by capturing experiments, ESR and liquid fluorescence detection. This work unveils more possibilities for modifying Z-scheme heterojunction system to improve photocatalytic performance.