Enhanced visible-light photocatalytic degradation of oxytetracycline hydrochloride by Z-scheme CuO/Bi2WO6 heterojunction

Abstract

Oxytetracycline hydrochloride (OTC) has a complex structure that makes it difficult to biodegrade. Photocatalysis is an effective method for addressing OTC pollution. In the present study, a CuO/Bi2WO6 Z-scheme heterojunction was constructed for the photocatalytic degradation of OTC via the hydrothermal method. XRD, SEM, TEM, XPS, UV–vis DRS, PL, FT-IR, BET, and Electrochemical workstation were used to analyze the morphological features, crystal structure, light absorption properties, and photoelectrochemical properties of the catalyst. These results revealed that the enhanced photocatalytic ability was due to the increased absorption of visible light and the improved migration and separation of electron-hole pairs facilitated by the fabricated heterojunction. The optimized CuO/Bi2WO6 heterojunction demonstrated a superior OTC removal efficiency of 86.3 % under visible light irradiation, approximately 2.6 times higher than pure Bi2WO6. Furthermore, the removal efficiency of OTC remained around 80 % even after five cycles. Free radical trapping experiments and ESR characterization indicated that •O2- and h+ were the main active substances. Finally, the Z-scheme electron transfer mechanism for the degradation of OTC by the CuO/Bi2WO6 heterojunction was proposed. And the intermediates were determined by LC-MS to speculate on possible OTC degradation pathways during the photocatalytic process. Thus, this study provides valuable insights into designing highly efficient Z-scheme heterojunctions to remove organic pollutants using a simple hydrothermal method.