Mechanochemical synthesis of a Z-scheme Bi2WO6/CuBi2O4 heterojunction and its visible-light photocatalytic degradation of ciprofloxacin

Abstract To efficiently remove the organic pollutants from water, the binary heterojunction photocatalytic hybrid Bi2WO6/CuBi2O4 was synthesized through a one-step mechanochemical operation. The results of XRD, FTIR and XPS analyses indicated that the formation of the binary components, as well as that of the heterojunction with a matched band structure, can be synchronously conducted in a solid-state system. The Bi2WO6/CuBi2O4 hybrids exhibited excellent photocatalytic activity towards ciprofloxacin (CIP) degradation under simulated sunlight (λ > 420 nm). The 10% Bi2WO6/CuBi2O4 sample showed the optimal photocatalytic activity by achieving over 90% degradation of CIP in 180 min with a rate constant of 0.01282 min−1. Electrochemical impedance spectroscopy, photocurrent response and Mott-Schottky analysis indicated that the hybrid exhibited high separation and migration efficiency of photogenerated charge carriers owing to its p–n heterojunction structure and the corresponding high redox capability. The study of the photocatalytic mechanism demonstrates that the charge transfer path conforms to the Z-scheme model, in which h+ and •O2− play a crucial role. This research provides strong practical support for the mechanochemical preparation of Z-scheme high-efficiency photocatalytic materials.