Fabrication of a Z-Scheme CeO ₂/Bi ₂O ₄ Heterojunction Photocatalyst with Superior Visible-Light Responsive Photocatalytic Performance

Abstract

In this study, a CeO₂/Bi₂O₄ Z-scheme heterojunction was prepared by using a facile hydrothermal method. After 40 min of visible-light irradiation, this composite photocatalyst displayed superior photocatalytic activity for removing of levofloxacin and methyl orange than those of neat CeO₂ and Bi₂O₄, achieving the degradation efficiencies of 88.75% and 90.3%, respectively. According to the results of transient photocurrent response, electrochemical impedance spectroscopy, and photoluminescence, it can be concluded that CeO₂/Bi₂O₄ heterojunction photocatalysts exhibited the most efficient separation of photoinduced charges. The enhanced photocatalytic performance was due to synergy between efficient separation of photogenerated carriers and increased solar absorption. A Z-scheme heterojunction between CeO₂ and Bi₂O₄ was formed, which was contributed by the well-matched band structure, facilitating the fast transfer and separation of carriers. The active species, including h⁺, ·O₂^–, and ·OH, play key roles in the photodegradation reactions, demonstrated by electron spin resonance spectroscopy. High-performance liquid chromatography–mass spectrometry was used to identify the probable degradation path of levofloxacin. This work will benefit the design of separable and efficient Z-scheme heterojunction photocatalysts for environmental remediation.

Keywords: CeO2/Bi2O4, Z-scheme heterojunction, Photodegradation, Levofloxacin, mechanism