Fabrication of a Z-scheme CeO2/Bi2O4 heterojunction photocatalyst with superior visible-light responsive photocatalytic performance

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 levofloxacin and methyl orange than pure 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, CeO2/Bi2O4 heterojunction photocatalyst exhibited efficient photoinduced charges separation. 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 efficient Z-scheme heterojunction photocatalysts for environmental remediation.