Enhanced photocatalytic activity of magnetic core–shell Fe₃O₄@Bi₂O₃–RGO heterojunctions for quinolone antibiotics degradation under visible light

A magnetically separable Fe₃O₄@Bi₂O₃–RGO core–shell heterostructured photocatalyst was successfully prepared through a self-assembly method for the first time. The Fe₃O₄ nanoparticles with an average diameter of 200 nm was wrapped by approximately 50 nm thick layer of Bi₂O₃ to form unique Fe₃O₄@Bi₂O₃ nanospheres, then loaded on the surface of reduced graphene oxide (RGO). Compared with pure Bi₂O₃ and Fe₃O₄@Bi₂O₃, the as-synthesized Fe₃O₄@Bi₂O₃–RGO nanocomposites showed broadened visible light adsorption range, increased charge separation efficiency, excellent photocatalytic activity and cyclic stability for degradation of quinolone antibiotics (QAs) under visible light irradation. The degradation rate of ciprofloxacin (CIP) with Fe₃O₄@Bi₂O₃–RGO photocatalyst could reach 98.3% in 240 min and it was still above 80% after ten photocatalytic reaction cycles. More importantly, benefiting from the introduction of Fe₃O₄ and RGO, the Fe₃O₄@Bi₂O₃–RGO nanocomposites could effectively prevent the rapid recombination of photogenerated electron–hole pairs and photocorrosion phenomenon of Bi₂O₃, which made it become a highly stable and durable photocatalyst. These attractive features make the Fe₃O₄@Bi₂O₃–RGO nanocomposites to be a promising photocatalyst for visible light photocatalytic degradation of QAs in water pollutants treatment.