Fabrication of the flower-flake-like CuBi2O4/Bi2WO6 heterostructure as efficient visible-light driven photocatalysts: Performance, kinetics and mechanism insight

Effective sunlight harvesting to realize environmental remediation remains great challenge for photocatalysis technique. Herein, the visible-light-driven CuBi2O4/Bi2WO6 hierarchical nanocomposites were synthesized via a facile hydrothermal method. Compared to the pristine CuBi2O4 and Bi2WO6, all the CuBi2O4/Bi2WO6 nanocomposites exhibited the superior photocatalytic activity toward tetracycline (TC) degradation under visible light irradiation (λ > 420 nm). Particularly, 60 wt% CuBi2O4/Bi2WO6 nanocomposite displayed the best photocatalytic activity, which can degrade 93% TC (20 mg/L) in 1 h with the rate constant of 0.0286 min−1. Based on the COD removal, the apparent quantum yield was calculated to be 0.32%. The superior photocatalytic performance of the CuBi2O4/Bi2WO6 nanocomposite is mainly attributed to: I) the efficient interfacial charge separation of the Z-scheme heterojunction; II) the prolonged lifetime of the charge carriers; III) the enlarged hierarchical surface area; IV) the strengthened visible light absorption. The DFT calculations suggested that the photoexcited electrons were transferred from the Bi2WO6 conduction band consisting of W5d orbital to recombine with the holes in the CuBi2O4 valence band consisting of O2p orbital of, which greatly facilitated the charge separation in the heterostructure. This study could provide some enlightment to the heterojunction construction and visible light utilization for other catalytic system.